Infrared absorption intensities of nitrous acid (HONO) fundamental bands

A Fourier transform spectrometer with a resolution of 0.06 cm^-1 was used to measure the absorption intensities of the four in-plane fundamental bands (v₁, v₂, v₃ and v₄) of trans-nitrous acid (HONO) and three of the in-plane fundamental bands (v₁, v₂ and v₄) of cis-nitrous acid. The equilibrium constants for the reactions NO + NO₂ + H₂O?2HONO, NO + NO₂?N₂O, and 2NO₂?N₂O₄ were used to determine the partial pressure of HONO in the gas mixture in the absorption cell. Interferences from overlapping absorptions of NO₂, H₂O and other species were digitally subtracted from the spectra.     

Laser Stark spectroscopy of DCN and DC15N

Using a CO laser, laser Stark resonance spectra were measured for the CN stretching fundamentals (the 00⁰1-00⁰0 bands) of D¹²C¹⁴N and D¹²C¹⁵N near 1925 cm^?1. Laser Stark resonances were also measured for the hot band 01¹1-01¹0 of D¹²C¹⁴N. In addition to accurately determining the band centers, dipole moments are given for the different vibrational states involved.     

Charge density wave transport in a novel inorganic chain compound, (TaSe4)2I

We report the observation of nonlinear conductivity with a well-defined threshold electric field E_T, and frequency dependent ac conductivity, in a novel linear chain compound, (TaSe₄)₂I. The material undergoes a phase transition to a semiconducting phase at T ～ 260 K, and nonlinear and frequency dependent transport is observed below this temperature. We argue that the material is a new example of collective mode transport provided by a Peierls-Fröhlich charge density wave condensate.     

Infrared spectrum of CS2: “Hot” bands associated with the 2185 cm−1 band and evidence for the CS2 laser assignment

The 10⁰100⁰0 band of CS₂ has been measured with a resolution of 0.030 cm^?1. The following “hot” bands associated with this transition were also measured and analyzed: 11¹101¹0, 12⁰102⁰0, 12²102²0, 13³103³0, 20⁰110⁰0, 30⁰120⁰0, 21¹111¹0, and 22⁰112⁰0. In addition, the 10⁰100⁰0 bands of the isotopic species ¹³C³²S₂, ¹²C³²S³³S, and ¹²C³²S³⁴S were measured in natural abundance. With the results of these measurements it is shown that the 02⁰112⁰0 transitions do indeed coincide with the CS₂ laser transitions, as do the 00⁰110⁰0 transitions. New arguments are given favoring the latter assignment.     

High-resolution measurement and analysis of the infrared spectrum of nitric acid near 1700 cm−1

The infrared spectrum of the ν₂ band of nitric acid (HNO₃) has been measured with a tunable diode laser in the frequency interval from 1690 to 1727 cm^?1. A total of 430 assigned transitions have been analyzed to yield a set of nine rovibrational constants for the upper state with a standard deviation of 0.0012 cm^?1. The band is primarily B type with a band center at 1709.568 ± 0.005 cm^?1. Because of the absence of perturbations, the band constants can be used to calculate transition frequencies and relative intensities with a high degree of accuracy.     

Laser Stark measurements on OCS including the observation of zero-field-forbidden ΔJ = 0, ±2 transitions

Laser Stark measurements have been made on the 02⁰000⁰0 and 03¹001¹0 vibrational transitions of ¹⁶O¹²C³²S, ¹⁶O¹²C³⁴S, and ¹⁸O¹²C³²S, and on the 03¹001¹0 transition of ¹⁶O¹³C³²S, using a CO₂ laser. In addition to providing dipole moment information for excited vibrational states, these measurements give vibrational band centers accurate to several megahertz. To aid in optical pumping experiments, several near coincidences between CO₂ laser transitions and OCS absorption lines are discussed. Electric-field-allowed ΔJ = 0 transitions are observed for the 2ν₂ band of ¹⁶O¹²C³²S and ¹⁶O¹²C³⁴S, as well as ΔJ = 2 transitions for the same band of ¹⁸O¹²C³²S.     

New nonlinear conduction mechanisms in charge-density-wave condensates in two or three space dimensions

It is shown that in phase-pinned charge-density-wave condensates an external electric field induces thermally activated continuous creation of new domains, when the pinning potential is periodic in the phase π of the condensate wave function. The mechanism gives rise to a nonlinear dc conductivity at finite temperatures, which seems to account for the anomalous conductivity observed in NbSe₃.