Scott J. Thomas

Rotational relaxation rate constants for CO2

Rotational relaxation rate constants, krot, have been measured for the CO2 00°1 level in three kinds of amplifiers: one using CO2 alone and two others using mixtures of CO2–He and CO2–N2. The experiment consists of perturbing the CO2 00°1 level with a ∼2‐nsec saturating pulse at P(20) in the 10.4‐μ band and monitoring the subsequent repopulation of the J = 19 rotational state with a probe beam set at P(20) in the 9.4‐μ band. The determined rate constants are kCO2–CO2 = 1.3±0.2, kCO2–He = 0.6±0.1, and kCO2–N2 = 1.2±0.2, all in units of 107 sec−1 Torr−1.

Analysis of the CS2–O2 Chemical Laser Showing New Lines and Selective Excitation

We investigated the lasing oscillation resulting from the flash photolysis of carbon disulfide and oxygen and found 270 new lasing lines which all could be ascribed to P‐ and R‐branch, vibrational‐rotational transitions in CO, a reaction product. A measurement of the time of initiation of the lasing lines showed that the CO was being selectively excited at two vibrational levels by two different mechanisms (collision with electronically excited SO2 and chemical formation of excited CO).

Observation of interband Faraday rotation at 10.59‐μ wavelength in room‐temperature Ge, CdTe, and GaAs

Room‐temperature interband Faraday rotation has been measured in samples of intrinsic germanium, doped cadmium telluride, and gallium arsenide at 10.59‐μ wavelength, in magnetic fields up to 80 kG. Measurements with a 7‐mm‐diam incident beam indicate that at least 33 dB isolation and a figure of merit exceeding 100 deg/dB should be attainable in a practical device based on either of the first two materials.

Plasma Temperatures Generated by Focused Laser Giant Pulses

Plasma temperatures generated by focusing ruby‐laser giant pulses on surfaces of Be, Al, and Pb in a vacuum were measured as a function of time and giant‐pulse intensity. The monochromatic emission intensities of the plasmas (relative to those obtained with a standard source) were measured at wavelengths ranging from 4000 to 10 500 A, and the temperatures were then calculated from the Planck function. It was found that the plasma temperatures achieved with the lighter elements were hotter and had greater rates of increase with laser intensity. However, the rates of increase were proportional to only the 0.5 power of the laser intensity or less, and the difference in temperatures between target materials was not very great. Temperatures as high as 8×105 °K were achieved with beryllium.

A NEW KIND OF RAPID‐SCAN MONOCHROMATOR USEFUL FOR ANALYZING CHEMICAL LASERS

A new rapid‐scan monochromator useful for analyzing chemical lasers has been evaluated. It consists of using a grating as part of the laser cavity and rotating one of the laser mirrors. The lasing lines are individually Q‐switched, increasing their intensities by a factor of 105. No limitation was found in the scan speed, and the theoretical spectral resolution of the grating was achieved. Because of the wavelength selection in the laser cavity, lines are brought out which otherwise would not lase.