[3] Klemperer's early work concentrated on the infrared spectroscopy of small molecules that are only stable in the gas phase at high temperatures.

It also led Klemperer to recognize the potential of molecular beams in spectroscopy, and in particular the use of the electric resonance technique to address fundamental problems in structural chemistry.

[4] Klemperer introduced the technique of supersonic cooling as a spectroscopic tool,[5] which has increased the intensity of molecular beams and also simplified the spectra.

The radio telescope data showed an isolated transition with no hyperfine splitting; thus there were no nuclei in the carrier of the signal with spin of one or greater nor was it a free radical with a magnetic moment.

Laboratory spectra of HCO+ (taken later by Claude Woods et al.,[9]) proved him right and thereby demonstrated that Herbst and Klemperer's models provided a predictive framework for our understanding of interstellar chemistry.

Before Klemperer introduced spectroscopy with supersonic beams, the spectra of weakly bound species were almost unknown, having been restricted to dimers of a few very light systems.

He foresaw that he could synthesize dimers of almost any pair of molecules he could dilute in his beam and study their minimum energy structure in exquisite detail by rotational spectroscopy.

Nowadays it is routine for microwave and infrared spectroscopists to follow his "two step synthesis"[10] to obtain the spectrum of a weakly bound complex: "Buy the components and expand."