Microwave Spectroscopy in the Region from Two to Three Millimeters, Part II

Abstract

Precise frequency measurements on rotational transitions occurring in the wavelength range from 2 to 3 mm for a number of molecules have been made. From these, centrifugal stretching effects have been determined and accurate values of the rotational constants obtained. A table including all frequencies so far measured in this region of the spectrum is given.

Determination of A 0 for CH3F from ground-state combination differences

“…Gordy and his group have published several progressively improved sets of rotational constants [2][3][4][5][6]. As can be seen from figure 1, comparison of GSCD predicted using the 1966 values [6] with the present experimental values differ by 4 x 10 -3 cm -1 at worst.…”

“…Only six of the nine rotational constants of formula (1) are used in (2). They are the same that play a part in the normal infra-red GSCD that we could call J-type GSCD.…”

“…In fact, it is easy to see that the expression for QK(J)-PK(J+ 1) or RK(J )-Qtc(J+l) is identical to (2), while expression such as RK(J--1)--PK(J+I) are derived in a straightforward way. It is to be noted that AK=K'-K" plays no part in these expressions.…”

Submillimeter-wave spectrum of carbonyl sulfide: rare isotopic species

“…In the 1950s the frequency region covered was further extended to over 100 GHz as frequency multipliers were introduced to microwave spectroscopy. Gordy and his collaborators developed efficient multipliers: 121.6 GHz for J ¼ 10-9 in 1951 [4], 218.9 GHz for J ¼ 18-17 in 1953 [5], 291.8…”

Hyperfine Structure in the Microwave Spectrum of NF3

“…This coaxial tortion constant D J (2), and a Stark effect measurement of expansion results in linewidths (FWHM) from Ç5 to 10 kHz the dipole moment in 1952 (3). This was followed by a millimein argon carrier gas.…”