Master equations for thermal unimolecular reactions and the reverse thermal recombination reactions are solved for a series of model reaction systems and evaluated with respect to broadening factors. It is shown that weak collision center broadening factors F(cent) (wc) can approximately be related to the collision efficiencies β(c) through a relation F(cent) (wc) ≈ max {β(c) (0.14), 0.64(±0.03...

We determine the linewidth of the hyperfine structure a10 component of R(56) 32-0 transition of I2 at 532 nm using the dependence of the peak amplitude of the third-derivative signal on the modulation width. We also use the same method to investigate pressure broadening and power broadening of the a10 component. 2005 Elsevier B.V. All rights reserved.

Water and carbon monoxide are two major compounds in the predominantly H2 atmospheres of stars, brown dwarfs and extrasolar planets. Recent radiative transfer models suggest that there is an urgent need for data on the pressure broadening of molecular transitions by H2 at high temperatures. We present a set of theoretical H2 pressure broadening parameters for 228 H2O transitions in the range of...

For some time there has been a discrepancy between theoretical and experimental values of microwave absorption in the terrestrial atmosphere. We felt that this is due to shortcomings in the theoretical treatment of pressure broadening when the significant overlap between adjacent lines occurs. Formal theories of pressure broadening have been given but have not been applied to the specific case ...

Selected isolated rotational transitions in the 1-0 band of the red A(2)Π-X (2)Σ(+) system in CN have been recorded with transient frequency modulation spectroscopy as a function of argon pressure up to 0.2 atm at room temperature. Line shapes were fit using Fourier transforms of a parametrized time correlation function, including Doppler and velocity-dependent collisional broadening, and colli...

Velocity modulation spectroscopy has been investigated in the terahertz region, employing pure rotational transitions of ArH and rotation-tunneling transitions of H3O + to study the competition between pressure broadening and Doppler broadening on the lineshapes, neutral suppression, and modulation efficiency. Velocity modulation is demonstrated to be effective to frequencies as low as 60 cm , ...