Predissociation spectra of the H5O2+.Ar(1,2) cluster ions are reported in the 1000-1900 cm(-1) region. The weakly bound argon atoms enable investigation of the complex in a linear action mode, and the resulting spectra are much simpler than those reported previously in this region [Asmis et al., Science 299, 1375 (2003) and Fridgen et al., J. Phys. Chem. A 108, 9008 (2004)], which were obtained using infrared multiphoton dissociation of the bare complex. The observed spectrum consists of two relatively narrow bands at 1080 and 1770 cm(-1) that are likely due to excitation of the shared proton and intramolecular bending vibrations of the two water molecules, respectively. The narrow linewidths and relatively small (60 cm(-1)) perturbation introduced by the addition of a second argon atom indicate that the basic "zundel" character of the H5O2+ ion survives upon complexation.
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http://dx.doi.org/10.1063/1.1834566 | DOI Listing |
J Phys Chem A
August 2024
JILA and Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309-0440, United States.
We report the infrared photodissociation spectrum of tagged protonated valine in the range 1000-1900 cm, prepared in a cryogenic ion trap. Comparison of experimental results with calculated infrared spectra based on density functional theory shows that the hydroxyl group of the carboxylic acid functionality and the protonated amine group adopt a configuration. Nitrogen and methane molecules were used as messenger tags with optimal tagging temperatures of 30 K for N and 60 K for CH.
View Article and Find Full Text PDFEur J Mass Spectrom (Chichester)
February 2019
1 Department of Chemistry, Memorial University, St John's, Canada.
The gas-phase structure of protonated β-methylaminoalanine was investigated using infrared multiple photon dissociation spectroscopy in the C-H, N-H, O-H stretching region (2700-3800 cm) and the fingerprint region (1000-1900 cm). Calculations using density functional theory methods show that the lowest energy structures prefer protonation of the secondary amine. Formation of hydrogen bonds between the primary and secondary amine, and the secondary amine and carboxylic oxygen further stabilize the lowest energy structure.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2018
Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
The structure and activity of peptides and proteins strongly rely on their charge state and the interaction with their hydration environment. Here, infrared photodissociation (IRPD) spectra of size-selected microhydrated clusters of cationic acetanilide (AA, N-phenylacetamide), AA-(HO) with n ≤ 3, are analysed by dispersion-corrected density functional theory calculations at the ωB97X-D/aug-cc-pVTZ level to determine the stepwise microhydration process of this aromatic peptide model. The IRPD spectra are recorded in the informative X-H stretch (ν, ν, ν, amide A, 2800-3800 cm) and fingerprint (amide I-II, 1000-1900 cm) ranges to probe the preferred hydration motifs and the cluster growth.
View Article and Find Full Text PDFJ Mass Spectrom
March 2016
Department of Chemistry, Memorial University of Newfoundland, St. John's, NL, A1B 3X7, Canada.
The structures of singly and doubly (and for Mg, triply) hydrated group 2 metal dications bound to deprotonated uracil were explored in the gas phase using infrared multiple photon dissociation spectroscopy in the mid-infrared region (1000-1900 cm(-1) ) and the O-H/N-H stretching region (2700-3800 cm(-1) ) in a Fourier transform ion cyclotron resonance mass spectrometer. The infrared multiple photon dissociation spectra were then compared with the computed IR spectra for various isomers. Calculations were performed using B3LYP with the 6-31 + G(d,p) basis set for all atoms except Ba(2+) and Sr(2+) , for which the LANL2DZ or the def2-TZVPP basis sets with relativistic core potentials were used.
View Article and Find Full Text PDFJ Am Soc Mass Spectrom
March 2014
State Key Laboratory and Institute of Elemento-Organic Chemistry, Nankai University, Collaborative Innovation Center of Chemical Science and Engineering, 300071, Tianjin, China,
To better understand inconsistencies between the predicted infrared (IR) spectra of previously suggested isomers of Lys2H(+) reported by Wu et al. (J. Am.
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