Novel laser gain and time-resolved FTIR studies of photochemistry

Several techniques are discussed which can be used to explore laboratory photochemical processes and kinetics relevant to planetary atmospheres; these include time-resolved laser gain-versus-absorption spectroscopy and time-resolved Fourier transform infrared (FTIR) emission studies. The laser gain-versus-absorption method employed tunable diode and F-center lasers to determine the yields of excited photofragments and their kinetics. The time-resolved FTIR technique synchronizes the sweep of a commercial FTIR with a pulsed source of light to obtain emission spectra of novel transient species in the infrared. These methods are presently being employed to investigate molecular photodissociation, the yields of excited states of fragments, their subsequent reaction kinetics, Doppler velocity distributions, and velocity-changing collisions of translationally fast atoms. Such techniques may be employed in future investigations of planetary atmospheres, for example to study polycyclic aromatic hydrocarbons related to cometary emissions, to analyze acetylene decomposition products and reactions, and to determine spectral features in the near infrared and infrared wavelength regions for planetary molecules and clusters

Last Day, Final Reflections

Well, here we are: my last day of summer internship. I am quite proud of what I accomplished this summer, although I had hoped to be just a little bit farther on the cataloging. Oh, well. It’s not like the books are going anywhere, right? And I’m not going anywhere, either, so hopefully I can finish the cataloging over the course of the fall semester, and continue to add to my LibGuide. [excerpt

Published and Proud

Today was an exciting day at work: my Bisexual and Transgender LibGuides are published and available to the public!! Excuse me as I squeal in nerdy glee. I made a couple of small changes before I published them: I added a user feedback box so that visitors to the LibGuide can let me know what they think, as well as changing some titles of boxes after Jess pointed out that they were in Librarian-speak instead of Normal College Student. I also took the LGBTQ landing page from its half-baked state to make it an officially “under-construction” welcome page. In case you are curious, here is the link to my LibGuide: http://libguides.gettysburg.edu/aecontent.php?pid=355859&sid=2910307 [excerpt

More Cataloging, More LibGuide

The way I have unified the LGBTQ titles—all 700-odd of them—is by using a local information field in the catalog. Quick cataloging lesson for you non-librarians: when I talk about subject headings, for example Gay Culture, those go in a field designated by the number 650. This means that it’s a universal, standardized field and that the headings in those fields will be recognized anywhere. For local subject headings, those that are only used within one library (ours, in this case), the field is designated by the number 690. I’m using one of those 690 fields with the heading “LGBTQ Resources” so that if you want to see all of the books in the collection that relate to more than one part of the LGBTQ acronym, you can do a search for subject and input LGBTQ Resources, and you’ll get the list. [excerpt

First Snag, One LibGuide Done!, and Why Cataloging Helps Patrons

Working on my transgender LibGuide started off smoothly, but I ran into a problem when I went back later and tried to follow the links to the online reference collection. None of the links worked! Trying not to panic, I went into the Gale Virtual Reference Library and looked for any hint of a permanent link to the reference sources. No such luck. Jess was out of her office in a meeting and I didn’t know who else was in the reference office, so I decided to try to solve the problem on my own. Then, inspiration struck: I searched Muscat for the titles of the online encyclopedias. Success! Each of them had a permanent link in the catalog, just like the physical books I’d linked to on a different part of the LibGuide page. Now I’m curious as to why Muscat can have a permanent link to the GVRL and I can’t, but I’ll try not to be bitter about it. Problem solved, and I can go back to playing with my LibGuide page! [excerpt

Hello! Or, How I Got Here

If you frequent the library, chances are you’ve seen me at the circulation desk. I’ve been a circulation desk assistant since my freshman orientation almost two years ago. I’ve loved libraries, books, and reading since before I started kindergarten, so the library seemed like a natural place for me to find my on-campus job. I soon fell in love with working at the desk; I particularly liked when I got to go into the stacks to look for an item that a patron couldn’t find or that had been requested for Inter-Library Loan. [excerpt

Bisexuality Week! (With an Aside on My Growing Librarian Instincts)

As I mentioned last week, this week I began work on my Bisexuality LibGuide. Actually, I finished work on it too. Now that I’m more familiar with how to build a LibGuide and now that I have a template for how I want my pages to work, it didn’t take very long to get the bones of the page laid out. I just needed to find the items in various categories with which to fill in the page. [excerpt

Laboratory studies of low temperature rate coefficients: The atmospheric chemistry of the outer planets

The purpose of the project is to perform laboratory measurements of reaction rate coefficients at low temperature. The reactions and temperatures of interest are those that are important in the chemistry of the hydrocarbon rich atmospheres of the outer planets and their satellites. In this stage of the study we are investigating reactions of ethynyl radicals, C2H, with acetylene (C2H2), methane (CH4), and hydrogen (H2). In the previous status report from 24 Jan. 1992, we reported on the development of the experimental apparatus and the first, preliminary data for the C2H + C2H2 reaction

Innovative methods for the measurement of I* quantum yields and kinetics by diode laser gain-versus-absorption

The quantum yields of a variety of candidate molecules for solar lasant materials to produce I* were tested. The absorption spectrum was measured for each compound and the I* yield determined by the diode laser or by infrared emission, using C3F7I as a standard. The results of these measurements are summarized. A GaAsInP diode laser system was developed to probe I and I* atoms to obtain yields and kinetics. A technique of gain-versus-absorption spectroscopy was investigated to measure quantum yields with high accuracy. The errors in the yield data were reduced to +/- 2% or less. In addition, experiments were set up to measure the rates of F-sublevel changing collisions in both the I ground state and the I* excited state. Finally, experiments and modelling were carried out to explore the possibility of measuring the recombination rates of I* with C3F7 radicals

Absolute 1* quantum yields for the ICN A state by diode laser gain versus absorption spectroscopy

Absolute I* quantum yields were measured as a function of wavelength for room temperature photodissociation of the ICN A state continuum. The temperature yields are obtained by the technique of time-resolved diode laser gain-versus-absorption spectroscopy. Quantum yields are evaluated at seven wavelengths from 248 to 284 nm. The yield at 266 nm is 66.0 +/- 2% and it falls off to 53.4 +/- 2% and 44.0 +/- 4% at 284 and 248 respectively. The latter values are significantly higher than those obtained by previous workers using infrared fluorescence. Estimates of I* quantum yields obtained from analysis of CN photofragment rotational distributions, as discussed by other workers, are in good agreement with the I* yields. The results are considered in conjunction with recent theoretical and experimental work on the CN rotational distributions and with previous I* yield results