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This paper reports that the absorption spectra of H2O+ have been measured by tunable mid-infrared diode laserspectroscopy in the spectral range of 1100–1380 cm-1. The H2O+ ions are generated in an AC glow discharge of the gaseous mixtures of H2O/He and detected with the velocity modulation technique. Forty new lines are assigned to theν2 fundamental band of H2O+(2B1). The observed lines together with other data published previously are fitted to the standard effective Hamiltonian of an asymmetric top, yielding a set of improved rotational constants, spin-rotation constants and their quartic and sextic centrifugal distortion constants for the ν2=1 vibrational state of H2O+.

The property of quantum nonlocality in the atom-field coupling system via degenerate Raman processes with cavity damping is investigated. It is found that if the cavity dissipation is very weak, the atom-field state can exhibit quantum nonlocality periodically. The rapidity of the loss of the quantum nonlocality depends on the amplitude of the initial coherent state and the cavity damping constant. The stronger the field is and the larger the damping constant could be, the more rapidly the nonlocality decreases.

A simple model has been developed to describe the Zeeman patterns of far-infrared laser magnetic resonance spectra of the monobromomethyl radical CH2Br observed at 447.3 and 671.1mum. A satisfactory agreement between the experimental spectra of the radical and their simulation with this simple model has been achieved. This approach can be used to gain further information about the structure and the spectrum of this interesting radical.

A global analysis of all available and identified spectra of the PO2 radical has been performed. In this analysis, the infrared spectra of the nu(3) band, the microwave and far infrared laser magnetic resonance transitions in the ground state are fitted simultaneously to the effective Hamiltonian for asymmetric top molecules. Since the analysis absorbs reliable experimental data extensively, it bears the most precise and most complete set of molecular constants for PO2. These molecular constants can, be used to reproduce the spectra of PO2 accurately. Attention is also paid to the similarity and difference between PO2 and NO2.

Twenty-five new R-branch lines of the v2 (1−←0+) band of H3O+ are measured using diode laser velocity modulation spectroscopy between 1070 and 1230 cm−1. The H3O+ ions are produced in a high voltage ac discharge with water diluted in helium. The observed lines together with all the previously published measurements are fit to the standard vibration-rotational Hamiltonian of an oblate symmetric top, yielding a set of improved molecular constants. All the sextic centrifugal distortion constants for both 0+ and 1− states are determined precisely. The observed R(13,0) transition is shifted about -0.129 cm−1 from its calculated value, indicating that a near degeneracy exists between the (13, 0)+ and (13, 3)− ground-state rotation-inversion levels.

Starting from the Watson A-reduced Hamiltonian and considering the infrared transitions with DeltaK(a) = 0, DeltaK(c) = +/-1 (A-type) or DeltaK(a) = +/-1, DeltaK(c) = +/-1 (B-type), and the far-infrared transitions with DeltaK(a) = 0, +/-2 and DeltaK(c) = +/-1, we calculate all the possible infrared absorption and far-infrared emission transitions of the v(4) and v(9) bands of 1,1-difluoroethylene (CH2CF2) pumped by 10P10 and 10P12 CO2 laser lines. We assign four previously unassigned CH2CF2 far-infrared laser lines (291.3 mum, 339.3 mum, 349.51 mum and 657.9 mum), where K-a and K-c represent the quantum number K of the limiting prolate top and the limiting oblate top, respectively. The 291.3 mum line is identified as being generated from the cascade transition. The assignment of the 288.5 mum line by Lafferty et al. (J. Mol. Spectrosc. 87(1981)416) is also confirmed.

High order centrifugal distortion terms have been derived and added to the effective Hamiltonian of asymmetric top molecules. Based on this Hamiltonian, a program in Fortran 77 has been developed for spectral analysis of asymmetric top molecules. The high order centrifugal distortion terms are found to be non-negligible even for the low-lying rotational transitions of molecules, such as H2 18O, subjected to severe centrifugal distortion effect, and for the high-lying rotational transitions of molecules, such as 14N16O2 subjected to the moderate centrifugal distortion effect.

An intracavity CO laser magnetic resonance spectrometer with homogeneous dc electric field applied via a pair of parallel Stark plates in the absorption cell is used to measure the electric dipole moments of free radicals. Taking advantage of the high sensitivity and high resolution of this technique and the Stark effect, highly-resolved saturated absorption spectra of the ν = 1-0 transition of 15N16O in the ground state X2Π3/2 have been successfully observed in the presence of a low electric field. The electric dipole moment of NO in the electronic ground state is determined as µ = 0.1566±14 D (Debye) from the analysis of the observed spectra, confirming that, combined with the Stark field, the laser magnetic resonance technique can be an effective and reliable approach for the precise measurement of electric dipole moments of free radicals, especially unstable ones.