Spectroscopy of Molecular Ions

Abstract

Traditionally, molecular ions have been studied by mass spectrometers or ion-counting techniques. The great sensitivity and versatility of these techniques are clearly attested to by the vast amount of mass spectrometric literature. However, it is equally true that mass spectroscopy has its limitations; basically, it provides one only with a charge-to-mass ratio for an ion. Obviously, all quantum state information is lost, particularly the vibrational and rotational, and usually even the electronic distributions of the ions. Similarly, no structural information such as bond lengths and angles is obtained. Indeed, in some cases the information obtained is so slight that one cannot even write a structural formula for the ion or distinguish between different chemical isomers.