MWIR DOUBLE RESONANCE SPECTROSCOPY OF THE HCN DIMER
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Date
1992
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Publisher
Ohio State University
Abstract
We have observed microwave-infrared double resonance (MWIRDR) signals in the vibrational upper suite ($v_{1}$)of the HCN dimer. With the IR laser locked onto the R(2) transition, the microwaves were scanned over the $J^{\prime}=3 -> 4$ transition, yielding a 400 kHz broad feature. In contrast, the $J^{\prime}=0 -> 2$ transition in propyne shows a DR signal consisting of two 60 kHz, residual Doppler broadened, lines, separated by 110 kHz. The two absorptions result from the Duppler shift between the colinearly launched MWs and their backreflection from metal surfaces. In the apparatus. The larger width of the dimer line reflects the combined effect of unresolved hyperfine structure due to the electric quadrupoles on both $^{14}N$ nuclei, and the lifetime broadening. The vibrational predissociation lifetime of this complex is now known to be within a range about one order of magnitude wide (previously more than three !). At the conference we hope to present data of the $HC^{15}N$ dimer MWIRDR experiments presently underway in our laboratory.
Description
Author Institution: Department of Chemistry, Princeton University