A new instrument has been constructed that couples a supersonic expansion source to a continuous wave cavity ringdown spectrometer using a Fabry–Perot quantum cascade laser (QCL). The purpose of the instrument is to enable the acquisition of a cold, rotationally resolved gas phase spectrum of buckminsterfullerene . As a first test of the system, high resolution spectra of the vibrational band of have been acquired at . To our knowledge, this is the first time that a vibrational band not previously recorded with rotational resolution has been acquired with a QCL-based ringdown spectrometer. 62 transitions of the three isotopologues of were assigned and fit to effective Hamiltonians with a standard deviation of 14 MHz, which is smaller than the laser frequency step size. The spectra have a noise equivalent absorption coefficient of . Spectral simulations of the band indicate that the supersonic source produces rotationally cold molecules.
A quantum cascade laser cw cavity ringdown spectrometer coupled to a supersonic expansion source
Brian E. Brumfield, Jacob T. Stewart, Susanna L. Widicus Weaver, Matthew D. Escarra, Scott S. Howard, Claire F. Gmachl, Benjamin J. McCall; A quantum cascade laser cw cavity ringdown spectrometer coupled to a supersonic expansion source. Rev. Sci. Instrum. 1 June 2010; 81 (6): 063102. https://doi.org/10.1063/1.3427357
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