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Spectral emissivities of the overtone and combination bands of H2O in the 1‐ to 2‐μ region have been measured between 1000° and 2200°K. The hot water vapor samples were produced in a small supersonic burner using H2 and O2. The measurements were made at the exit of the burner where the interactions of the hot gas jet with the ambient atmosphere are small. The variation of the spectral emissivities of H2O in the optically thin absorption region as a function of temperature are given for a total pressure of 1 atm and a constant amount of H2O in the optical path.The integrated intensities of the bands have been determined from the emissivity spectra at the various temperatures. The values of the integrated intensities of the 1.87‐, 1.38‐, and 1.14‐μ H2O bands at 273.2°K are 26.0, 21.2, and 1.92 (cm—2·atm—1), respectively. The integrated intensity variations with temperature of the bands have been used to determine the absolute intensity contributions from the numerous overtone and combination transitions whi...

The temperature dependencies of the total integrated intensities of vibrational—rotational band systems are discussed and general expressions are given for the temperature dependencies for the harmonic oscillator approximation. The derived dependencies indicate that while the total integrated intensity of a fundamental is independent of temperature, the integrated intensity of an overtone or combination band system increases with increasing temperature. The theoretically derived temperature dependencies are compared with available experimental data and good agreement is found where self absorption within the test gas does not influence the experimental results.

The absolute intensities of the two infrared active fundamentals of the ammonium ion, ν3 and ν4, have been studied in several environments. Dilute solid solutions of NH4+ ions in KCl, KI, CsCl, and CsI were studied and compared with pure NH4I. After separating the effect of the net charge, the apparent bond moments ranged from 0.63 d to 0.80 d (av 0.71) and the bond dipole derivatives, ∂μ/∂r, from 2.06 d/A to 3.59 d/A (av 2.80 d/A). The bond moment is substantially the same as in NH3.

Measurements have been made of the total integrated band intensities of the 5.3‐μ fundamental and the 2.7‐μ first overtone bands of NO in the temperature range 1400° to 2400°K. The NO gas sample was studied at high temperatures using a reflected shock‐wave technique.Within the temperature range used in the present experiments, the integrated band intensity of the NO fundamental does not vary. However, the integrated intensity of the first overtone band of NO shows a small temperature dependence. The temperature dependencies of the two bands are in agreement with theoretical temperature dependencies determined assuming a harmonic oscillator approximation to the NO molecule. Using the theoretical temperature dependencies the experimental data have been extrapolated to give values of the integrated intensities α° at STP. The values of α° obtained for the fundamental and first overtone bands of NO are 76±7 cm—2·atm—1 and 2.8±0.5 cm—2·atm—1, respectively.

A shock‐wave technique is described which provides a means of measuring the infrared integrated intensity of molecular bands at elevated temperatures. The total band emission from the high‐temperature gas region existing between the end plate of a shock tube and the reflected shock wave was measured using a rapid‐response infrared detector. The total emission of the band is obtained as a function of pathlength as the reflected shock wave recedes from the end plate. The initial concentration, shock velocity, and reflected‐shock pressure were measured and the final conditions of the test gas were calculated from the normal shock relations.The method has been used to measure the absolute intensity of the 2.7 μ band of CO2 (ν1+ν3 and 2ν2+ν3) in the temperature region 1200° to 3000°K. The shock‐heated samples were produced in a 4% CO2—96% Ar mixture using helium as a driver gas. To ensure adequate pressure broadening at high temperatures for this weak band and yet to remain within the optically thin region, th...

The monohydrates of the hydrogen halides exist as ionic crystals. The infrared spectra of OH3F, OH3Cl, OH3Br, OH3I, and OD3Cl at —195°C showed the four fundamental frequencies expected for a symmetrical pyramid at about 1100 cm—1 (ν2), 1700 cm—1 (ν4), 2600 cm—1 (ν1 or ν3), and 3200 cm—1 (ν1 or ν3). The high‐frequency bands, which are very broad at —195°C, did not sharpen on cooling to 8°K, indicating that their breadth is caused by some frozen‐in disorder.

Measurements have been made of the total absolute integrated intensities of the 4.7‐μ fundamental and 2.4‐μ first overtone band systems of CO at various temperatures within the range 2500° to 5000°K. The CO gas sample was studied in emission using a reflected shock wave to raise the sample to the high temperatures. Effects of vibrational relaxation, dissociation, and shock structure have been considered in the data interpretation.Within the temperature range used in the present experiments, the integrated intensity of the CO fundamental band system remains constant. However, the integrated intensity of the CO first overtone band system shows a small increase with increasing temperature. The temperature dependencies of the two band systems are in agreement with the theoretical temperature dependencies. The present experimental results for CO extrapolated to STP are 289±29 and 2.3±0.3 cm−2·atm−1 for the total integrated band intensities of the fundamental and first overtone band systems, respectively.