Rotational action spectroscopy of trapped molecular ions

Abstract

Rotational action spectroscopy is an experimental method in which rotational spectra of molecules, typically in the microwave to sub-mm-wave domain of the electromagnetic spectrum (∼1–1000 GHz), are recorded by action spectroscopy.

Leak-out Spectroscopy, a universal method of action spectroscopy in cold ion traps

“…In this double resonance approach one would detect the change in the LOS signal when the rotational population of the ensemble of trapped ions is changed by a mm-wave radiation source as demonstrated earlier for other action spectroscopy methods. 10 Moreover, LOS reveals the spectrum of the bare ion, C 3 H + in the present case, and does not suffer from spectral shifts due to a tag as the comparison with the spectra of the photodissociation (IRPD) of the C 3 H + -Ne complex shows. 14 Therefore, LOS opens a whole suite of possibilities to record spectra of mass selected ions with an unprecedented sensitivity.…”

“…Even pure rotational spectra could be obtained by the use of double resonance schemes combining millimeter wave excitation of rotational states with infrared lasers to create an action spectroscopic signal which is altered by the rotational excitation. 10 Despite the success story of action spectroscopy, many important ions could not be studied in high resolution so far, the reason being, e.g., a missing adequate reaction for LIR, or ineffective complex formation for LIICG.…”

An ion mobility mass spectrometer coupled with a cryogenic ion trap for recording electronic spectra of charged, isomer-selected clusters

“…The approach, which works particularly well for molecular ions cooled in a supersonic expansion or in an ion trap, has been used to obtain infrared and electronic spectra for a vast array of charged molecules using light from tunable benchtop lasers and optical parametric oscillators, and free electron lasers. Other forms of action spectroscopy, including laser induced reaction 20 and laser suppression of clustering, 24 which also possess the advantages of mass-selectivity and high sensitivity, have also been deployed to probe infrared and electronic transitions of molecular ions.…”

Microsolvation of H2O+, H3O+, and CH3OH2+ by He in a cryogenic ion trap: structure of solvation shells

“…As a result of the longer time for cluster growth, often larger X + He n clusters can be formed in the trap than in the plasma expansion. This approach has been widely adopted by several groups to form X + He n clusters around smaller and larger cations, 34,[36][37][38][39][40] such as inorganic and small hydrocarbon ions, 8,35,[41][42][43][44][45][46] C 60 + , [47][48][49] and protonated PAH (coronene) 50 and biomolecules, 35,39 as well as reaction intermediates. 38 However, in many of these studies, He-tagging is barely used for spectroscopy of the bare X + ion and no or only little attention has been paid to the X + Á Á ÁHe interaction potential.…”