Microwave Spectroscopy at High Temperature-Spectra of CsCl and NaCl

New opportunities and emerging themes of research in microwave spectroscopy

“…NH 3 was the first stable polyatomic molecule to be identified in the interstellar medium (Cheung et al 1968). H 2 O (Cheung et al 1969) and H 2 CO (Snyder et al 1969) were detected during the following year. Many molecules of varying size and complexity have since been identified through radioastronomy.…”

“…Later experiments extended the range of systems. High-temperature ovens (Stitch et al 1952) were used to generate gas-phase species containing refractory metals. Organic molecules of increasing complexity were studied as researchers became interested in measuring the energetic barriers to internal rotation about the axes of C-C bonds (Wilson 1951).…”

Interpreting the Microwave Spectra of Diatomic Molecules

“…The predicted value of 2B from the electron diffraction value is 4000 MHz (See Supplementary Materials, Excel file CsCl.xlsx). The spectrum of cesium chloride in the region 24.3-25.4 GHz was measured [38] at 715 • C, and the frequencies observed (error 1.5 MHz) are given in Figure 7. Inspection of the eight frequencies demonstrates that there appears to be just one major grouping of frequencies.…”

“…This problem makes an excellent student exercise (Appendix A) without the complicating effects of multiple J and/or isotopes. Comparison of microwave spectra of cesium chloride from two sources (Grouping 0 (orange) [38], Grouping 1 (blue) [31]). The pedagogical goal achieved here is showing that the vibrational assignments should always be checked by comparison of the predicted B e ratios.…”

“…Potassium has two isotopes, 39 K and 41 K, present in approximately a 14:1 ratio. The predicted value of 2B from electron diffraction is 3300 MHz (see Supplementary Materials, Excel file KI.xlsx).…”