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

Müller, David; Dopfer, Otto

doi:10.1039/d2cp01192a

Cited by 4 publications

(2 citation statements)

References 108 publications

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“…Prior to conducting EPD experiments, we measured the EI mass spectrum of Dia using the ReTOF (Figure 4(a)). Minor differences in the relative intensities of the fragments compared to earlier spectra reported by Cupas et al (1965) and Waltman & Ling (1980) are a result of the slightly mass-dependent ion transmission of the orthogonal ReTOF, which is known to vary somewhat with the timing of the extraction pulses (Günther et al 2017;Müller & Dopfer 2022). As previously observed, the mass spectrum of Dia is unusual among most hydrocarbons, in that the parent radical cation peak (m/z 188) is also the base peak.…”

Section: Ei and Pd Mass Spectramentioning

confidence: 56%

“…The ions were stored for 45 ms in the trap held at 5 K and cooled by an intense He buffer gas pulse to effective (ro)vibrational temperatures between 15 and 20 K (Günther et al 2017;Müller et al 2019;Müller & Dopfer 2020a. To confirm that the ions were indeed cold prior to spectroscopic interrogation, the setup was periodically tested by He-tagging of CH 3 + produced from EI of methanol, which can occur in the 22-pole trap only for ions with T < 20 K (Asvany et al 2018;Müller & Dopfer 2022). Additionally, the lowest vibrational mode of Dia + has a calculated vibrational frequency of 228 cm −1 , which corresponds to a vibrational temperature of 328 K. Thus, all ions should populate the ground vibrational state in the ground electronic state, and contributions of hot bands in the EPD spectrum are not expected.…”

Section: Experimental and Computational Techniquesmentioning

confidence: 99%

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Optical Spectrum of the Diamantane Radical Cation

Crandall

Radloff

Förstel

et al. 2022

ApJ

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Similarities exist between the infrared spectra of diamondoids and unidentified infrared emission bands seen in the spectra of young stars with circumstellar disks. Due to their low ionization energy and absorption in the visible range, the radical cations of these highly stable molecules are also suggested to contribute to the well-known but largely unassigned diffuse interstellar bands. However, thus far only the optical spectrum of the adamantane cation (Ada+) has been measured in the laboratory, which is required for astronomical identification. Herein, we present the optical spectrum of the diamantane radical cation (C14H20 +, Dia+, D 3d) between 400 and 1000 nm in the gas phase. The spectra are obtained by electronic photodissociation (EPD) of mass-selected ions generated by electron ionization and trapping in a cryogenic trap at 5 K. The most intense fragmentation channels are the losses of H and C4H9. The optical spectrum reveals two broad and unresolved bands centered near 760 and 450 nm that are assigned to the D 2(2 E u) ← D 0(2 A 1g) and D 5(2 A 2u) ← D 0(2 A 1g) transitions using density functional theory. Despite a vibrational temperature below 20 K, no vibrational structure is resolved. Franck–Condon simulations of the D 5 ← D 0 transition predict intense vibronic progressions that become indiscernible from the band contour at spectral widths above 350 cm−1. Thus, the lack of resolved spectral features is attributed to lifetime broadening, Franck–Condon congestion arising from geometric changes, and possibly vibronic coupling. In addition to the EPD spectra, we characterize the ground state of Dia+ by analysis of a remeasured photoelectron spectrum and a predicted infrared spectrum.

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