Ground State ¹⁴N Quadrupole Couplings in the Microwave Spectra of N,N′-Dimethylaniline and 4,4′-Dimethylaminobenzonitrile

Abstract

Microwave spectra of N,N'-dimethylaniline and 4,4'-dimethylaminobenzonitrile have been recorded in a pulsed supersonic jet using chirped pulse techniques. Experimental substitution structures have been determined for both molecules by detection of the spectra of all (13)C and (15)N isotopomers in natural abundance using a broadband spectrometer. Additionally, a narrowband spectrometer has been used to reveal the (14)N quadrupole splittings at high resolution, from which the orbital occupancy numbers of the amino- and cyano-nitrogen atoms have been determined. An apparent direct relationship between these values and the barriers to inversion of the amino groups is discussed.

Chirped-pulsed FTMW spectra of valeric acid, 5-aminovaleric acid, and δ-valerolactam: A study of amino acid mimics in the gas phase

“…Preliminary CP-FTMW data were obtained using a modified spectrometer that resembles the instrument developed by the Pate group [14]. The modified spectrometer employs a mirror-horn cavity [15] to reduce the power requirements while retaining some of the broadband capabilities of the original machine. Liquid VA was placed in an external sample container and entrained in 1 bar of He.…”

A Ka-band chirped-pulse Fourier transform microwave spectrometer

“…During the past few years, the applications of chirped-pulse spectroscopy have been numerous, including the study of metal-containing molecules [3][4][5][6], conformationally rich molecules [7], and molecular clusters [8]. Chirped-pulse instruments have also been developed to work over reduced bandwidths and at low frequency [9,10].…”

A direct digital synthesis chirped pulse Fourier transform microwave spectrometer

“…A similar CP-FTMW spectrometer with one horn and one focusing mirror has also been demonstrated in perpendicular 23 and coaxial 24 arrangements. The setup presented here is similar to the last setup, except the microwave mirror has been replaced by microwave foam so that the backwards going emission is detected (Figure 1).…”

“…8 The signal-to-noise of the instrument in both the DDS and AWG configurations is lower than the original Pate lab spectrometer, 8 due to the polarization power available (50 W versus 2 kW), but comparable to other low power (<100 W) CP-FTMW spectrometers. 9,11,13,23,25 …”