Ronald M. Lees

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The C-N stretching infrared fundamental of CH(3)NH(2) has been investigated by high-resolution laser sideband and Fourier transform synchrotron spectroscopy to explore the energy level structure and to look for possible interactions with high-lying torsional levels of the ground state and other vibrational modes. The spectrum is complicated by two coupled(More)
The quantum solid para-hydrogen (p-H2) has recently proven useful in matrix isolation spectroscopy. Spectral lines of compounds embedded in this host are unusually narrow, and several species have been reported to rotate in p-H2. We found that a p-H2 matrix inhibits rotation of isolated methanol (CH3OH) but still allows internal rotation about the C-O bond,(More)
NH3 absorption spectra have been recorded from 6460 to 6522 cm 1 at room temperature and 5.5 Torr pressure with an external cavity tunable diode laser. The spectra served (a) as an initial test of a multipass optical assembly mounted in a large vacuum chamber designed for future slit nozzle experiments, (b) to further our understanding of the(More)
A new technique for high resolution photoacoustic detection based on application of laser diodes has been developed. This method was tested and compared using identical photoacoustic instrumentation (cell and microphone) to study gas absorption in three different spectral regions, namely: the infrared range near 2100 cm(-1), CO and OCS fundamental band(More)
In this work, terahertz and Fourier transform far-infrared (FTFIR) synchrotron spectra of methyl mercaptan, CH(3)SH, have been investigated in order to provide new laboratory information for enhanced observations of this species in interstellar molecular clouds and star-forming regions. Like its methanol cousin, methyl mercaptan has particularly rich(More)
  • Zhen-Dong Sun, Ronald M Lees, Li-Hong Xu
  • The Journal of chemical physics
  • 2010
We report saturation dip spectroscopy in the C-N stretching band of CH(3)NH(2) with a resolution of 0.4 MHz and an accuracy of 0.1 MHz by use of a CO(2)-laser/microwave-sideband spectrometer. The wide tunability, Lamb-dip resolution, absolute frequency accuracy, and high sensitivity of our dual-mode instrument were all key features in making precise(More)
Lamb-dip spectroscopy of the C-N stretching band of methylamine has been systematically extended to P-, Q-, and R-branch by using microwave sidebands of a large number of CO2 laser lines as frequency-tunable infrared sources in a sub-Doppler spectrometer. Lamb-dip signals of more than 150 spectral lines have been observed with a resolution of 0.4 MHz and(More)
Studying the energy level structure of di€erent molecules by means of spectroscopy is one of the ®elds in physics and chemistry. In this paper, we describe a knowledge-based system, molecular spectroscopic assignment assistant (MOSAA), which can assist researchers in the assignment of the far-infrared and infrared absorption peaks of the molecules in(More)
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