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chem dork awesomeness

October 11, 2007

Mmm so I know that most of you won’t understand this, but I’m going to type it anyway.
I met with this grad student today about what work I can do for her on my eight week rotation in her lab. She works for the Chemical Bonding Center, which has the awesome goal of trying to take a video of a single molecule vibrating. :-)
So first the setup. They use a femtosecond laser (the prefixes go mili micro nano pico femto, so there are 10^15 femtoseconds in a second) with some crazy optics to split it into three beams. The optical table where the laser is set up is covered with tiny mirrors, lenses, and prisms, prolly nine or so per square foot. Just craziness. The laser comes out of the generator purple, gets changed to green in two places and yellow in one place, with the wavelengths chosen to create a coherent vibration in the molecule and then stimulate it’s relaxation, and then focused on the sample. Then BOOM out of the sample comes a fourth laser, this time blue.
But wait, a word about the sample. So they want to measure a solution that contains a single molecule. Fiiiirst this involves dilution of the sample so that there’s just one molecule. Then they have to figure out how to observe something so very tiny, and they’ve got an awesome way to do it. First, they picked this molecule, I forget it’s name, that’s long and organic and highly conjugated. This means lots of optical activity because of the free pi electrons. That’s still not enough though, so they went to the nano-scientists. They got this group at another UC to attach two silver balls to each end of the molecule. These balls act like an antenna…sorta. I studied this effect last year with my two projects. Silver nano-particles have sweet light amplification properties, and the magic is that they do it twice. First, the incoming light pulse is amplified by the balls (it creates a plasmon resonance) before it hits the sample. Then the signal pulse coming from the sample molecule is amplified a second time by the balls, basically resulting in 4x amplification. Sweetness indeed.
All this awesomeness comes together in that blue pulse that comes out of the sample. It’s got crazy cool information about how the molecule is moving because of the incoming laser pulses. Lotsa math later, we have a clear idea of exactly what that molecule did during that time period.
Yeah this research is definitely on the list of projects I want to work on for grad school. Femtosecond lasers, plasmons, absurd amounts of math. Sweetness.
Anyway, this was a study break from reading a looooong article on NOPAs, or non-collinear optical parametric amplifiers, or the bits of the above setup which change the colors. So back to work!

6 Comments leave one →
  1. Anonymous permalink
    October 11, 2007 4:34 pm

    After a quick visit to wikipedia to look up ‘plasmon’, I think I understand everything you said. It sounds WAY awesome :D
    Have I told you I’m seriously considering going into Physical Chemistry? I’m actually doing well in that class. It’s surprising.

  2. October 11, 2007 4:35 pm

    blarg, that was me forgetting to sign in.

  3. October 11, 2007 8:00 pm

    Haha way to be. YaY for pchem! You should do it and come here! *laughs* Just remember, learn more math and physics. And maybe some programming…basically just take all the hard courses that you can. Dude, how come you’re never online??

  4. Anonymous permalink
    October 11, 2007 9:36 pm

    The short answer is I’ve been busy, but I need to try to be online more because I haven’t talked to you in a while! I’ve been in super-study mode, but it’s payed off. I think I have A’s in everything except the Chem 462 lab. I have no idea how I did on the first lab report yet. But I study too much, as everyone is always telling me. And I think I’m feeling it now. So in the future, slightly less studying (only slightly), slightly more forced free time.

  5. October 11, 2007 9:37 pm

    and that was me forgetting to log in AGAIN. Should have slept more last night.

  6. October 11, 2007 10:33 pm

    Hah yeah junior year is often super-study time. I totally burnt out first term. The new rule, after that, was that for at least one night on the weekend I don’t have to do homework. But that’s awesome that you’re doing so well. I want As…*laughs* then again, it’s grad school. I’ll prolly get a lot of As because something like a B- is failing. The curves are insane.

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