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[Music]

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thanks to introduction so as he

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mentioned I'm Haley I work with Susanna

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would expire at Emory University and a

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lab focuses on measuring a rotational

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spectrum of complex organic molecules

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for the purpose of comparing them to

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radio telescope data to start mapping

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out the chemical composition of the

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interstellar medium and my particular

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project is on the moon ethanol at the

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moment so I'm going to be talking about

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that today so we use radio telescope

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data to map out as I mentioned the

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interstellar medium radio telescopes

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such as Alma look in the submillimetre

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microwave regime which gives us

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rotational spectra of molecules now you

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can imagine we have hundreds of

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molecules in the interstellar medium and

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you have a telescope pointing in a

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particular area and it measures

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everything in its line of sight so you

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can imagine say we have a hundred

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different molecules and they're all

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overlaid on each other in one big

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spectrum so trying to deconvolution

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which molecules are actually in that

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spectrum is very very difficult and so

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we our lab looks at measuring web-based

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rotational spectra so that we can

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directly compare it to a radio telescope

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data so that we can determine

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composition so rotational spectroscopy

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is in the gas phase that's the only way

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that molecules can rotate but gas phase

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model story actually reproduce the

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abundances that we observe in space in

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space the the accepted theory today is

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the surface chemistry of a stellar eye

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screens so you have a composition of ice

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such as water methanol and nh3 ices and

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these come in contact with cosmic rays

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UV radiation and it starts to dissociate

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these more complex species down into

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these radical forms upon upon approach

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to a say a protozoa

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Cora warmer region these radicals can

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migrate in the ice and start to

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recombine and that's how we form even

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more

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by excel getting cc's as this ice warms

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up even further these complex molecules

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can then be dissolved from the surface

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of the ice and that's how we detect the

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gas phase and so these four molecules

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here dimethyl ether a methyl amine

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ethanol and ethylene glycol are

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predicted to form from these ice

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dissociation products and each for all

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four of these have actually been

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detected in the interstellar medium so

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as I mentioned our target molecule at

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the moment is a minima which is also

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predicted to form from these these

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isotherm dissociation products but I'm

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going to give you a little bit of a

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rundown on rotational spectroscopy as a

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whole because that's what I'm mainly

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going to be talking about today just so

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you kind of understand I'm talking about

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so in the gas phase as I mentioned

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molecules are actually able to freely

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rotate vibrate and translate all at the

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same time so we have if you remember

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from undergrad if you ever took P chem

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there are three main types of molecular

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spectroscopy we have the electronic

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spectroscopy which kind of gives us

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information on what atoms are in our

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system we have vibrational spectroscopy

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which gives us functional group

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information which is kind of telling us

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if we have an O H group or a carboxylic

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acid or something like that but

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rotational spectroscopy really gives us

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that structural fingerprint so if we

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have two molecules with the same atoms

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in them similar rearrangement but

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there's just a slight different

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conformational change rotational

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spectroscopy can tell us the exact

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conformation of a molecule so it's very

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very useful in that sense so to give you

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an eye the reason that we measure these

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different types of molecular

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spectroscopy so electronic is kind of

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from your visible optical region and up

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infrared is where we do our vibrational

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spectroscopy and then our radio

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microwave submillimetre region is where

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we do our rotational spectroscopy which

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is where telescopes such as Alma

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actually measure so a bit of an energy

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level diagram here this bottom one here

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is the ground electronic state and then

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we have an electronics excited state in

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this blue arrow here shows an electronic

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transition so it's quite a large energy

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gap within these electronic

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States we have these vibrational levels

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and so you can see here this red one is

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a vibrational transition and then within

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that again we have rotational

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transitions so you can very large

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magnitude of different rotational

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transitions depending on the electronic

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state and the vibrational state and so

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forth so it can get quite complex so

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starting with the simplest model a

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diatomic molecule so imagine you have

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two different atoms for rotational

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spectroscopy and molecule has to have a

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dipole moment and kind of think of that

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as having a break in symmetry so for a

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diatomic molecule you need two very

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different atoms if you have a ch2 for

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example if your atoms are the same

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you're not going to see it and see if

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you can imagine there's two axes running

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through so this one coming through here

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and say there's an axis going straight

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through the bond here if your molecule

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rotates around the bond axis you're not

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going to see anything so nothing's

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really changing right but if you drew an

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axis through here and your molecule

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rotates about the center of mass you're

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gonna see and change the dipole moment

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because your molecule is actually

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changing orientation diatomic molecules

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are quite simple in their spectra they

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have very even space energy level

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spacings we refer to them as two B where

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B is just your rotational constant which

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is input inversely proportional to your

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moment of inertia of your system so you

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get quite even spacings of your your

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transitions when you get to a more

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complex polyatomic system you need three

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different axes to define your molecule

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and we define molecules based on these

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moments of inertia so starting with your

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little linear molecule just like with

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your day I'll make an ax in a very

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similar way you move to a spherical top

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to something that is completely

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symmetric you can't see that and then

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you have your symmetric top which is

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where it starts getting a little bit

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more complicated so symmetric top is

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defined in two different ways

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which is just related to which moment of

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inertia which axis actually has a unique

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moment of inertia from there we move on

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to our asymmetric top which is the most

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complex situation that we can have for

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example just this water molecule with

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three atoms three different atoms has is

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an asymmetric top and has a very very

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complicated

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even though it's a very simple molecule

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so to give you an idea what they might

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look like compared to the diatomic

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spectrum I showed you before we get a

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very very complex spectrum this is the

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spectrum of glycol out and these are the

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magnitude of rotational constants that

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you need to fit something like an

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asymmetric top so as I showed before

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with the diatomic molecule you just need

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that B rotational constant whereas for

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an asymmetric top it gets much more

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complicated so we really need these

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laboratory-based spectra to try and fit

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imagine if you had a hundred of spectra

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like these overlaid on top of each other

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we need to try and decom believe that so

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that's what we do as I mentioned target

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molecules and you know methanol it's of

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prebiotic importance which is why we're

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interested in it specifically it's the

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precursor to glycine it's been predicted

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to be stable under interstellar

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conditions but it's very unstable under

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terrestrial conditions so you can't buy

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it in a bottle and even when you make it

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it dissociates and reacts away so

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quickly that we need to measure it

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almost exactly as we're making it so

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it's a very very different difficult way

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to try and make something and detect it

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at the same time as I mentioned it's

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predicted to form from interstellar

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green surface chemistry and there is no

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rotational spectrum of this molecule at

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all yes so the way that we proposed to

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make amino methanol is using a technique

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called it o singlet D insertion

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chemistry so a thing that we are going

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to that on the next slide but it's just

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an excited state of atomic oxygen and

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it's been shown in the past too readily

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insert into HX bonds where H is hydrogen

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and then X can be anything from carbon

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nitrogen oxygen or another hydrogen it's

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been shown that it has some kind of

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preference for carbon hydrogen months

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but it can absolutely insert into

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different ones so we propose to use the

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carbon hydrogen insertion of a singlet D

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into methyl amine to form amino methanol

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on the fly and then measure it as we're

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making it so as I mentioned I D is the

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first excited state atomic oxygen its

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ground state is a triplet P all I really

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want you to get away from this is

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singlet and triplet so singlet means

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your electrons are all paired and then

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in a triplet state you have two unpaired

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electrons but for reaction to occur

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the surfaces of these these molecules of

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these atoms have to overlap them the

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only way they can overlap is we're not

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the only way but what is that they have

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to have the same spin in order to

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overlap so a carbon hydrogen or

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molecular orbital all of our electrons

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are paired and so this surface only

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overlaps with our singlet D surface it

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doesn't overlap with the triplet piece

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so we can't have that insertion occur in

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the triplet piece state and since spin

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flip is forbidden in this action or in

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most cases so the way actually happens

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is the oxygen actually takes an electron

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from the carbon hydrogen highest

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occupied molecular orbital which is

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actually a bonding orbital so by taking

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that electron out of a bonding orbital

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you're decreasing that bond order so

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that bond breaks it gets weak it breaks

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and the oxygen is able to insert so a

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little bit on how we actually do that in

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the lab so this is a picture of my

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chamber we have a vacuum chamber we have

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my laser coming in and we have this

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silicon tube here I have a above my

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chamber I have a reaction mechanism

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where it makes all my molecules together

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and I mix ozone argon and methylene

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together they enter this tube and that's

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where they interact with the laser so

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the laser is specifically to interact

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with the ozone the ozone at 248

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nanometers breaks apart into O singlet D

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and therefore while in this tube the O

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singlet D can insert into methylamine

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for Mamina methanol and then we push it

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into our vacuum chamber this difference

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in pressure gradient causes it to

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rapidly expand which prevents further

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reactions from occurring and it also

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actually results in rotational and

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vibrational cooling of the molecules so

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that we can prove these low-lying

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rotational States and also the

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vibrational calling can prevent it from

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further dissociating we then improve the

280
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supersonic expansion with our

281
00:10:45,730 --> 00:10:42,320
submillimetre light and then detect the

282
00:10:47,740 --> 00:10:45,740
spectrum from there so in the past this

283
00:10:49,930 --> 00:10:47,750
technique specifically has been shown to

284
00:10:52,780 --> 00:10:49,940
work to produce methanol from a singlet

285
00:10:55,780 --> 00:10:52,790
the insertion into methane and here's

286
00:10:57,310 --> 00:10:55,790
just a few transitions of methanol to

287
00:10:58,110 --> 00:10:57,320
proof that it was actually methanol that

288
00:11:00,790 --> 00:10:58,120
we're making

289
00:11:02,949 --> 00:11:00,800
but methanol is quite stable so we

290
00:11:04,060 --> 00:11:02,959
wanted to show that an unstable species

291
00:11:06,040 --> 00:11:04,070
like immune and ethanol

292
00:11:08,650 --> 00:11:06,050
example can actually format something

293
00:11:10,510 --> 00:11:08,660
that's been obviously observed before so

294
00:11:12,730 --> 00:11:10,520
they form vinyl alcohol using a singlet

295
00:11:16,000 --> 00:11:12,740
D insertion into ethylene and again you

296
00:11:18,040 --> 00:11:16,010
can see that was successful so Nina

297
00:11:19,900 --> 00:11:18,050
methanol looking at the reaction energy

298
00:11:22,090 --> 00:11:19,910
diagram as I mentioned earlier singlet

299
00:11:25,060 --> 00:11:22,100
do you can insert insert into more than

300
00:11:28,420 --> 00:11:25,070
just the carbon hydrogen bond so we did

301
00:11:30,040 --> 00:11:28,430
a reaction profile energy diagram so

302
00:11:33,010 --> 00:11:30,050
that o singlet D inserts into the methyl

303
00:11:36,130 --> 00:11:33,020
amine and gives off a lot of energy and

304
00:11:38,590 --> 00:11:36,140
amino methanol is the most energy stable

305
00:11:40,840 --> 00:11:38,600
molecule it does give up about 152

306
00:11:43,780 --> 00:11:40,850
kilocalories per mole which will become

307
00:11:45,340 --> 00:11:43,790
important later on in my talk but the

308
00:11:49,600 --> 00:11:45,350
fact that it's the lowest energy species

309
00:11:52,980 --> 00:11:49,610
is likely to mean it's the highest the

310
00:11:55,480 --> 00:11:52,990
most prominent molecule in our spectrum

311
00:11:58,450 --> 00:11:55,490
from now use computational chemistry

312
00:11:59,920 --> 00:11:58,460
techniques so we just ran a theoretical

313
00:12:01,750 --> 00:11:59,930
calculation and grabbed out the

314
00:12:03,700 --> 00:12:01,760
rotational constants in the structure of

315
00:12:05,740 --> 00:12:03,710
the molecule the optimal structure and

316
00:12:07,120 --> 00:12:05,750
it gives us an ID so we simulate this

317
00:12:08,890 --> 00:12:07,130
spectrum using these rotational

318
00:12:10,420 --> 00:12:08,900
constants and it gives us an idea of

319
00:12:12,490 --> 00:12:10,430
where to look in our spectrum what sort

320
00:12:14,230 --> 00:12:12,500
of lines we're looking for maybe what

321
00:12:16,270 --> 00:12:14,240
region we should be expecting them to be

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in and then once we get the spectrum we

323
00:12:20,860 --> 00:12:17,930
can we can refine it from there you

324
00:12:22,210 --> 00:12:20,870
think this is our start point so

325
00:12:24,430 --> 00:12:22,220
starting with ozone as I mentioned

326
00:12:26,890 --> 00:12:24,440
that's my singlet D precursor here you

327
00:12:30,160 --> 00:12:26,900
can see we're detecting it and how in

328
00:12:32,170 --> 00:12:30,170
our system if I sit my frequency on the

329
00:12:35,010 --> 00:12:32,180
center of this transition here and

330
00:12:37,180 --> 00:12:35,020
monitor over time so the way that we

331
00:12:39,040 --> 00:12:37,190
introduce our molecules into the chamber

332
00:12:40,660 --> 00:12:39,050
is using a pulsed valve so actually

333
00:12:43,000 --> 00:12:40,670
pulses the gas into the chamber

334
00:12:45,520 --> 00:12:43,010
so as the pulsar opens at time zero you

335
00:12:47,140 --> 00:12:45,530
get this influx of ozone into the

336
00:12:49,060 --> 00:12:47,150
chamber which is what this is showing

337
00:12:51,310 --> 00:12:49,070
here and as your pulse valve closes your

338
00:12:52,600 --> 00:12:51,320
signal goes away at about this time here

339
00:12:55,930 --> 00:12:52,610
unfortunately this frequency doesn't

340
00:12:57,610 --> 00:12:55,940
show up the laser RFI but we do get an

341
00:13:00,850 --> 00:12:57,620
ozone signal depletion which is

342
00:13:02,770 --> 00:13:00,860
indicative of forming a single D from

343
00:13:04,300 --> 00:13:02,780
there we started it's been a while since

344
00:13:06,850 --> 00:13:04,310
this chamber had run an experiment like

345
00:13:09,000 --> 00:13:06,860
this so we went back to methanol to make

346
00:13:12,100 --> 00:13:09,010
sure we were still successfully

347
00:13:13,780 --> 00:13:12,110
inserting our singlet D so we introduced

348
00:13:16,450 --> 00:13:13,790
methane into the chamber with the ozone

349
00:13:17,180 --> 00:13:16,460
you can see here after that laser fires

350
00:13:21,559 --> 00:13:17,190
you can see that

351
00:13:24,800 --> 00:13:21,569
by again this is in time we start

352
00:13:27,009 --> 00:13:24,810
getting it influx of methanol signal and

353
00:13:29,480 --> 00:13:27,019
if you measure a multitude of different

354
00:13:32,300 --> 00:13:29,490
methanol transitions we are in fact

355
00:13:33,920 --> 00:13:32,310
making methanol but it's important to

356
00:13:36,350 --> 00:13:33,930
note that we have to use very specific

357
00:13:38,150 --> 00:13:36,360
techniques to train hone in on this

358
00:13:39,980 --> 00:13:38,160
signal because there's so much dead time

359
00:13:42,499 --> 00:13:39,990
when our molecule of interest actually

360
00:13:44,840 --> 00:13:42,509
isn't there so that makes spectral

361
00:13:46,340 --> 00:13:44,850
acquisition quite slow so I remove the

362
00:13:49,220 --> 00:13:46,350
methane from the system and decided to

363
00:13:51,350 --> 00:13:49,230
introduce the methylamine so here's just

364
00:13:52,610 --> 00:13:51,360
a snippet of a band wide scan which is

365
00:13:55,400 --> 00:13:52,620
how far we've come so far

366
00:13:57,740 --> 00:13:55,410
we've gone from about 140 to 200 25

367
00:14:00,259 --> 00:13:57,750
gigahertz he's just sniff it and you can

368
00:14:01,970 --> 00:14:00,269
see a multitude of different transitions

369
00:14:03,439 --> 00:14:01,980
in here and as you zoom in closer

370
00:14:06,259 --> 00:14:03,449
there's even more down in the noise

371
00:14:09,350 --> 00:14:06,269
there but so far all we've been able to

372
00:14:12,559 --> 00:14:09,360
identify is formaldehyde here's just the

373
00:14:15,800 --> 00:14:12,569
time and then the molecular signal with

374
00:14:17,119 --> 00:14:15,810
an amine and hydrogen cyanide we haven't

375
00:14:18,470 --> 00:14:17,129
been able to assign some of the other

376
00:14:21,110 --> 00:14:18,480
wines yet we're still working on that

377
00:14:23,900 --> 00:14:21,120
but these molecules are quite important

378
00:14:26,210 --> 00:14:23,910
because in a paper in 2005 by Feldman

379
00:14:28,790 --> 00:14:26,220
out at our he showed the dissociation

380
00:14:30,530 --> 00:14:28,800
pathways of amino methanol and if you

381
00:14:32,389 --> 00:14:30,540
can surmount a barrier of about 50

382
00:14:33,740 --> 00:14:32,399
kilocalories per mole which as I

383
00:14:35,990 --> 00:14:33,750
mentioned earlier that o singlet D

384
00:14:38,179 --> 00:14:36,000
reaction gives off about 150

385
00:14:40,639 --> 00:14:38,189
kilocalories per mole of energy we do

386
00:14:43,990 --> 00:14:40,649
actually dissociate into the main the

387
00:14:46,490 --> 00:14:44,000
main pathways formaldehyde and nh3 and

388
00:14:48,410 --> 00:14:46,500
methane amine and water so they are

389
00:14:50,720 --> 00:14:48,420
actually the molecules at least these

390
00:14:52,939 --> 00:14:50,730
two that we're seeing in our spectrum so

391
00:14:54,139 --> 00:14:52,949
we believe that we are actually making a

392
00:14:56,780 --> 00:14:54,149
mean a methanol while we haven't

393
00:14:58,970 --> 00:14:56,790
confirmed our detection yet but we think

394
00:15:01,819 --> 00:14:58,980
it's just associating before enters the

395
00:15:03,799 --> 00:15:01,829
chamber so we think maybe our lasers a

396
00:15:05,210 --> 00:15:03,809
little bit too high up that tube so

397
00:15:07,160 --> 00:15:05,220
maybe we're giving it a little bit too

398
00:15:10,280 --> 00:15:07,170
much time to react in the tube before it

399
00:15:11,990 --> 00:15:10,290
enters the expansion and so we're going

400
00:15:14,179 --> 00:15:12,000
to do some chemistry experiments and

401
00:15:16,369 --> 00:15:14,189
laser chemistry and rest of the tree but

402
00:15:19,160 --> 00:15:16,379
often rathalu laser up and down the tube

403
00:15:21,230 --> 00:15:19,170
to see if our chemistry changes from

404
00:15:23,240 --> 00:15:21,240
there obviously once we confirm the

405
00:15:25,460 --> 00:15:23,250
amino methanol detection we want to

406
00:15:29,059 --> 00:15:25,470
provide these rotational constants so

407
00:15:29,900 --> 00:15:29,069
that we can hope the community trying to

408
00:15:33,680 --> 00:15:29,910
TechEd it in the

409
00:15:35,030 --> 00:15:33,690
so medium from telescope observations we

410
00:15:36,820 --> 00:15:35,040
are having a little bit of trouble so

411
00:15:38,720 --> 00:15:36,830
Arizona is obviously very very active

412
00:15:43,010 --> 00:15:38,730
specifically it reacts very strongly

413
00:15:44,510 --> 00:15:43,020
with methylamine and and also we have

414
00:15:46,430 --> 00:15:44,520
like oxygen in the system there's so

415
00:15:48,050 --> 00:15:46,440
many other reactions that can be

416
00:15:51,080 --> 00:15:48,060
occurring and forming molecules in our

417
00:15:52,610 --> 00:15:51,090
system so one way we've thought to

418
00:15:54,860 --> 00:15:52,620
simplify our spectrum to hopefully

419
00:15:57,260 --> 00:15:54,870
detect it rather than react it away is

420
00:15:59,330 --> 00:15:57,270
to trap the ozone on silica beads

421
00:16:02,330 --> 00:15:59,340
because we do have our ozone generator

422
00:16:04,250 --> 00:16:02,340
creates about 1% ozone and o2 mixture

423
00:16:06,440 --> 00:16:04,260
and so if we can trap it on the beads we

424
00:16:09,560 --> 00:16:06,450
can remove that whole plethora of

425
00:16:11,090 --> 00:16:09,570
reactions from there so that's it for

426
00:16:12,320 --> 00:16:11,100
now I want to give a big shout out to

427
00:16:14,840 --> 00:16:12,330
the rest of the whiticus we've accrued

428
00:16:15,500 --> 00:16:14,850
specifically chase who's now my partner

429
00:16:17,240 --> 00:16:15,510
on the project

430
00:16:18,680 --> 00:16:17,250
I want to thank NASA for all the funding

431
00:16:20,640 --> 00:16:18,690
and the previous students who worked on

432
00:16:27,790 --> 00:16:20,650
the project

433
00:16:44,380 --> 00:16:42,230
Ian Mason talk we have a high 12 so what

434
00:16:47,960 --> 00:16:44,390
kind of detector are you using after

435
00:16:49,820 --> 00:16:47,970
step 3 this one yeah that's a hot

436
00:16:52,940 --> 00:16:49,830
electron thermometer it's set in Z so

437
00:16:54,620 --> 00:16:52,950
how much I like all your data happens in

438
00:17:16,750 --> 00:16:54,630
a matter of seconds

439
00:17:29,020 --> 00:17:23,620
for the computational hot wait sorry my

440
00:17:38,799 --> 00:17:29,030
bed for this one the which hydrogen

441
00:17:40,539 --> 00:17:38,809
bonds oh yes that was considered this

442
00:17:42,190 --> 00:17:40,549
calculation was done by a previous

443
00:17:45,520 --> 00:17:42,200
graduate student but I believe he did

444
00:17:47,190 --> 00:17:45,530
consider that but we ran a bunch of

445
00:17:51,190 --> 00:17:47,200
different calculations at different

446
00:17:54,640 --> 00:17:51,200
Theory levels to get the right yeah

447
00:17:58,419 --> 00:17:54,650
right to get the most likely structure

448
00:18:00,159 --> 00:17:58,429
for that but we are we are working on

449
00:18:01,899 --> 00:18:00,169
trying to improve this so we do get

450
00:18:04,390 --> 00:18:01,909
what's called hyperfine splitting in our

451
00:18:06,490 --> 00:18:04,400
spectrum so we're trying to add more

452
00:18:28,460 --> 00:18:06,500
terms to this calculation to try and get

453
00:18:44,270 --> 00:18:36,080
this energy difference oh I see it's

454
00:18:46,840 --> 00:18:44,280
easy um this is a various reaction all