Mass and Isotope‐Selective Infrared Spectroscopy

Abstract

Recent advances in laser spectroscopic techniques make it possible to obtain mass‐ and isotope‐selective infrared spectra of gas‐phase species at high resolution and reduced hot‐band spectral congestion. In these techniques, infrared excitation is coupled with ultraviolet multiphoton ionization and detection of the resulting ions in a mass spectrometer, which allows the separation of contributions of different isotopomers and, more generally, species of different mass in a mixture. In combination with jet cooling techniques, spectra are obtained for very cold molecules. These spectra can then be analyzed to extract information on dynamical processes such as intramolecular vibrational redistribution or tunneling and rearrangement processes, and on how intramolecular dynamics is influenced by vibrational excitation and isotope effects. In this review, we introduce isotope‐selective infrared spectroscopic techniques and present some selected applications on isotope effects and intramolecular dynamics of vibrationally excited chloroform, aniline, and benzene obtained by isotope‐selective infrared spectroscopy.

Fundamentals of Rotation–Vibration Spectra

“…Reviews covering effective Hamiltonian analyses include those by Quack (1990), Lehmann et al (1994), Nesbitt and Field (1996), Gruebele and Bigwood (1998), Perry et al (1996), and Herman et al (1999). In addition, more extensive references can be found in the article by Hippler et al 2011: Mass and Isotope-selective Infrared Spectroscopy, this handbook.…”

High‐ResolutionFTIRand Diode Laser Spectroscopy of Supersonic Jets

“…Further important experimental developments concern the combination of pulsed supersonic jets with continuous scan FTIR spectroscopy (Luckhaus et al 1995), a possibility, which was probably not anticipated by anyone, and the combination of pulsed supersonic jets with continuous laser cavity ring down spectroscopy, which provides very high sensitivity and very high resolution (1 MHz and potentially better), by Quack (1999, 2002). The combination of pulsed IR-laser spectroscopy of pulsed supersonic jets with ionization and mass-selective detection resulted in massand isotope-selective spectroscopy reviewed by Hippler and Quack (2005) and Hippler et al (2011): Mass and Isotope-selective Infrared Spectroscopy, this handbook. Such a mass-selective technique combined with supersonicjet FTIR spectroscopy had been suggested already by Quack (1990) but has not been realized, so far, as it is technically very demanding.…”

High‐Resolution Fourier Transform Infrared Spectroscopy

“…It will be possible using these techniques to record and analyze rovibrationally resolved low-lying modes of weak absorbers like large aromatic systems and hydrogen-bridged biomolecules in the electronic ground state. High-resolution FTIR spectroscopy also offers many possibilities for "combination techniques", for instance, by combination with supersonic jets or molecular beams and with laser technology, some of which we describe elsewhere in this handbook (Snels et al 2011 andHippler et al 2011). Albert, S. and Quack, M. (2007b) High resolution rovibrational spectroscopy of pyrimidine.…”

“…We mention here the benzene molecule (Hollenstein et al 1990, Domenech et al 1991, Pliva et al 1996 and its isotopomers (Snels et al 1997, Hippler and Quack 2005 and heterocyclic systems (Hegelund et al 2005a,b, Palmer et al 1998). In addition, high-resolution diode laser spectroscopy was carried out on fluoro- (Basterretxea and Escribano 2004) and chlorobenzene (Uskola et al 2000) and there have been studies by isotope-selective spectroscopy (Hippler et al 2003(Hippler et al , 2011: Mass and Isotopeselective Infrared Spectroscopy, this handbook). We have recently studied chloro-and fluorobenzene systematically using high-resolution FTIR spectroscopy (Albert et al 2006a, Albert and.…”