Related Experiment Video
Updated: Jul 6, 2026

Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers
Published on: August 18, 2017
Laser spectroscopy of a halocarbocation in the gas phase: CH2I+
Chong Tao1, Calvin Mukarakate, Scott A Reid
1Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881, USA.
Abstract:
We report the first gas-phase observation of the electronic spectrum of a simple halocarbocation, CH2I+. The ion was generated rotationally cold (Trot approximately 20 K) using pulsed discharge methods and was detected via laser spectroscopy. The identity of the spectral carrier was confirmed by modeling the rotational contour observed in the excitation spectra and by comparison of ground state vibrational frequencies determined by single vibronic level emission spectroscopy with Density Functional Theory (DFT) predictions. The transition was assigned as 3A1 <-- X1A1. This initial detection of the electronic spectrum of a halocarbocation in the gas phase should open new avenues for study of the structure and reactivity of these important ions.
Related Concept Videos
Chemical Ionization (CI) Mass Spectrometry
IR and UV–Vis Spectroscopy of Aldehydes and Ketones
IR and UV–Vis Spectroscopy of Carboxylic Acids
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency, 1710 cm−1. The C=O bond of the...
Spectroscopy of Carboxylic Acid Derivatives
In the...
IR Frequency Region: X–H Stretching
Mass Spectrum: Interpretation

