Chun Fu Su

Microwave detection of direct trans to gauche transitions in CH2DOH

Abstract Additional lines have been assigned in the microwave torsional-rotational spectrum of CH 2 DOH. Of particular interest is the detection and identification of direct trans to gauche transitions to both gauche states. In terms of torsional substate, three R -type and three Q -type transitions have been assigned for e 0 ( trans ) to e 1 ( gauche ) and four R -type transitions have been assigned for e 0 ( trans ) to o 1 ( gauche ). Five additional lines have been assigned for e 1 ( gauche ) to o 1 ( gauche ) and seven additional lines have been assigned within the e 0 and o 1 substates. The torsion-rotation analysis gives the torsional energy level differences gauche - gauche = 101.9 GHz, trans - gauche (lower) = 280.5 GHz, and trans - gauche (upper) = 382.4 GHz. The torsional potential energy coefficients have been determined to be V 1 = 8.74 ± 0.01 cm −1 , V 2 = 2.49 ± 0.02 cm −1 , and V 3 = 373.45 ± 0.05 cm −1 .

The microwave torsional-rotational spectrum of CHD2OD

Abstract The microwave torsional-rotational spectrum of CHD 2 OD has been predicted, identified, assigned, and analyzed to determine the internal rotation potential energy coefficients and nonrigidity corrections for the molecule. Although trans to gauche transitions are too weak for observation in the torsional ground states, transitions have been observed within and/or between three excited torsional states as well as the usual gauche (+) to gauche (−) transitions for the torsional ground states. Taken together, these allow for the determination of the potential energy coefficients. The potential energy coefficients for CHD 2 OD are V 1 = −8.73 ± 0.05 cm −1 , V 2 = −2.90 ±0.10 cm −1 , and V 3 = 365.00 ± 0.25 cm −1 .

Microwave spectrum of (cyanomethyl) cyclopropane

Abstract The microwave spectrum of (cyanomethyl) cyclopropane has been studied. Only the gauche form of the molecule has been observed. This is consistent with the infrared results where the gauche form is found to be the dominant form (>85%). The rotational constants for the ground vibrational state are (in MHz) A = 10 800.703, B = 2014.942, C = 1835.685. From Stark effect measurements, the dipole moment is found to be 3.89 ± 0.08 D. Rotational transitions in several excited vibrational states also have been measured and assigned.

Evaluation of a Numerical Method to Determine the Combustion Temperature of A Rocket Engine Simulator from OH Emission Spectra

The hydroxyl radical OH emission spectra generated by a rocket engine simulator have been recorded at various oxidizer (O2) pressures. Due to the Boltzmann distribution function and the effect of the linewidth on the lineshape, the calculated spectral line intensities are expected to be dependent upon the assumed temperatures and linewidth. The hydroxyl OH rotational spectra at various assumed temperatures with an optimal linewidth have been predicted and plotted. The line peak intensity ratios of three selected line peaks to the largest line peak have been computed. A polynomial fit process has been employed to establish an emperical relation between the line peak intensity ratios and the rotational temperatures. The line peak intensity ratios evaluated from the observed OH spectra along with the emperical relations have been used to determine the combustion temperature.