U. Andresen

An automatic molecular beam microwave Fourier transform spectrometer

We present hardware and software details of the pulsed molecular beam microwave Fourier transform (MB‐MWFT) spectrometer used in the Kiel microwave group. We emphasize an automatic scanning facility which greatly increases the efficiency of MB‐MWFT spectroscopy for the measurement of unassigned spectra.

Microwave Fourier‐transform spectrometer for the entire K band for the investigation of rotational spectra of molecules in the gas phase

We present the experimental set up of a microwave Fourier‐transform spectrometer for the entire K band from 18 to 26.4 GHz. It is hereby shown that this type of spectroscopy is achieved above 18 GHz. Advantages and disadvantages are discussed. The performance is illustrated by the recordings of rotational transitions of various molecules.

A microwave Fourier transform spectrometer in the region between 26 and 36 GHz

We present a first set up and tests of a microwave Fourier transform spectrometer above 26 GHz with some features differing from the instruments in the lower frequency bands.

The Effect of Deuteration on the Molecular Dipole Moments of Haloacetylenes

Abstract The dipole moments of chloro-, bromo-, and iodoacetylene, and those of the respective deuterated species, have been accurately determined using microwave Fourier transform spectrometers equipped with Stark cells. In each case, deuteration resulted in a change of the value of the dipole moment of about 0.012 D. The results provide strong evidence that the orientation of the dipole moment vector of iodoacetylene is opposite to that of the other haloacetylenes.

On the Measurement of Rotational Spectra of Monodeuterated Asymmetric Top Molecules in Natural Abundance Demonstrated for Monofluorobenzene

Abstract We report on the measurement of rotational transitions of monodeuterated fluorobenzene in natural abundance to show the feasibility of the investigation of monodeuterated asymmetric top molecules without the necessity of isotopic enrichment.

A Microwave Fourier Transform Spectrometer in the Region from 4 to 6 GHz with Double Resonance Modulation

Abstract We report on the experimental set up and performance of a microwave Fourier transform spectrometer for the G band from 4 to 6 GHz. The sensitivity, achievable linewidth, and resolution capability is demonstrated by measurements of rotational transitions of various molecules.

Microwave Spectrum and Nuclear Quadrupole Coupling of 2-Chloropyridine

The microwave spectrum of 2-chloropyridine, 2-Cl(C5H4N), has been studied to determine the 35Cl, 37Cl and 14N nuclear quadrupole coupling constants. The results are discussed within a simple MO theory. We propose an approximate r0-structure under certain assumptions. In addition to the ground state we observed one vibrationally excited state of both chlorine isotopic species of 2-chloropyridine.