K.-Q. Zhang

The infrared spectra of uracil, thymine, and adenine in the gas phase

Abstract The infrared spectra of gas-phase uracil, thymine, and adenine have been recorded from 100 to 3700 cm−1 at a resolution of 1 cm−1. The vibrational band positions and qualitative band intensities are reported and compared to published matrix data as well as to theoretical calculations. Our work suggests that gas-phase emission spectroscopy is a sensitive technique for recording spectra of organic and biological molecules.

Far-Infrared Emission Spectra of Selected Gas-Phase PAHs: Spectroscopic Fingerprints

The emission spectra of the gaseous polycyclic aromatic hydrocarbons (PAHs) naphthalene, chrysene, and pyrene were recorded in the far-infrared (far-IR) region. The vibrational bands that lie in the far IR are unique for each PAH molecule and allow discrimination among the three PAH molecules. The far-IR PAH spectra, therefore, may prove useful in the assignment of unidentified spectral features from astronomical objects.

Infrared spectra of hot HF and DF

New Fourier transform emission measurements were obtained for HF and DF at a temperature of 2300°C. Both pure rotation and vibration-rotation lines were measured with a precision of about 0.0005 cm-1. These new lines were combined with previously measured data to give improved rotational constants for the vibrational levels υ = 0-5. The HF molecule is the most convenient monitor of 19F abundances in cool stars.

High resolution infrared spectroscopy of cyanogen N‐oxide, NCCNO

We report here on the first high resolution infrared absorption spectra of the semistable nitrile oxide, NCCNO. All of the fundamental modes of vibration (except for the lowest‐frequency bending mode) and several combination bands have been measured with a Fourier transform spectrometer at a resolution of 0.005 cm−1. In this paper, we present analyses of υ4, the C–C stretching mode at 714.753 94(6) cm−1, υ6, the NCC bending mode at 403.925 97(6) cm−1, υ6+υ7 at 490.123 62(6) cm−1, and the tentatively assigned υ5+υ6 combination band at 826.291 86(8) cm−1. A simultaneous least squares fit of these four bands gives ground state rotational constants of B0=0.077 085 54(34) cm−1 and D0=4.570(30)×10−9 cm−1.

Infrared emission spectroscopy at 100 μm. Vibration—rotation spectrum of CsI

Abstract The vibration—rotation emission spectrum of CsI was recorded in the 110–130 cm −1 region of the spectrum. Although individual rotational lines were not resolved, we measured the positions of 29 band heads involving the vibrational bands from 1-0 to 30-29. These vibrational data when combined with previously measured microwave and millimeter-wave pure rotational transitions yielded improved Dunham constants. In addition, an experimentally derived Born—Oppenheimer potential is also reported and compared with the purely ionic internuclear potential of the Rittner model. The results reported here demonstrate that far-infrared emission spectroscopy is a very sensitive technique for detecting high-temperature molecules, even at wavelengths around 100 μm.