Engineering topics

Looney, J. P.

Publications and source records attributed to Looney, J. P..

3 records

NASA NTRS1992

Self-broadening and line mixing in HCN Q branches

A tunable difference-frequency laser has been used to record Q-branch spectra of the nu sub 1 + nu sub 2 (4004/cm) and nu sub 2 + nu sub 3 (2806/cm) combination bands, as well as the nu sub 1 - nu sub 2 (2599/cm) difference hot band of HCN, at 1-400 torr pressures. Line mixing is noted in the strongly overlapped, higher-pressure Q-branch profiles from the nonradiative Lorentzian superposition of the component transitions. An effective R to T transition energy-corrected-sudden scaling law is found to give a consistent and satisfactory fit to the Q-branch profiles of all three bands.

Pine, A. S.↗

NASA NTRS1990

Decoupling in the line mixing of acetylene infrared Q branches

A difference-frequency laser spectrometer was used to record the Q-branch profiles of the nu1 + nu5, nu3 + nu4, and nu2 + 2nu4 + nu5 Pi(u)-Sigma(g) combination bands in the 2.5 micron C-H stretch-bend region of acetylene. The experiment was carried out at pressures in the range of 1 to 500 Torr. It is shown that line mixing causes substantial deviation of collisionally overlapped Q-branch profiles from the independently additive superposition of Lorentzian line shapes. It is also found that the degree of line mixing is greatly reduced from that assuming all the broadening arises from rotationally inelastic collisions coupling Q-branch lines only to one another.

Pine, A. S.↗

NASA NTRS1987

Air broadening of the hydrogen halides. I - N2-broadening and shifting in the HCl fundamental

The resolvent operator formalism of Kolb, Griem (1964), and Baranger (1962) is used to determine the widths and shifts of the fundamental band vibration-rotation lines of HCl under N2 pressure. Time-development operator matrix elements are evaluated accounting for all bilinear and second order anisotropic terms, in addition to isotropic effects to all orders. The method employs the use of a parabolic trajectory model and explicit velocity averaging. The major contributions to the linewidths are found to arise from dipole-quadrupole, quadrupole-quadrupole, and vibrationally dependent isotropic dispersion forces. Good overall agreement is found between calculated and measured widths and linewidths over a 163-295 K temperature range.

Looney, J. P.↗