Chemistry Department Colloquium

"Old Problems Meet New Techniques: Applications of Frequency Comb-Referenced Spectroscopy"

Presented by Dr. Trevor Sears, Brookhaven National Laboratory/Stony Brook University

Monday, March 28, 2016, 11:00 am — Hamilton Seminar Room, Bldg. 555

I will describe some recent precision measurements of colliisonally-broadened line shapes in acetylene near 1.5 microns, then accurate rest frequency measurements for some hot band lines in the same region by sub-Doppler spectroscopy. Finally, we have recently been looking at the ammonia spectrum in the same wavelength region using the same techniques and find the observed partially resolved hyperfine splittings are diagnostic for individual rotational quantum number changes, so that the sub-Doppler lines can confirm or deny previous rotational assignments based on combination differences measured from Doppler-limited spectra. The measured hyperfine splittings should also give a signpost for potential ortho-para mixing that will occur in certain excited vibrational levels in NH3, and one observed transition showing anomalous hyperfine structure may indeed terminate in such a level. The presence of these mixed states has implications for the rates of ortho-para interconversion in the interstellar medium.

Hosted by: Greg Hall

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