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ID 18825
file
creator
Tabayashi, Kiyohiko
Yamamoto, Keisuke
Tamenori, Yusuke
Harries, James R.
Gejo, Tatsuo
Iseda, Mitsuhiro
Tamura, Takashi
Honma, Kenji
Suzuki, Isao H.
Nagaoka, Shin-ichi
Ibuki, Toshio
subject
organic compounds
molecular clusters
hydrogen bonds
dissociation
time of flight mass spectra
spectrochemical analysis
chemical exchanges
spectral line shift
red shift
reaction kinetics
abstract
Inner-shell excitation spectra and fragmentation of small clusters of formic acid have been studied in the oxygen K -edge region by time-of-flight fragment mass spectroscopy. In addition to several fragment cations smaller than the parent molecule, we have identified the production of HCOOH H+ and H3 O+ cations characteristic of proton transfer reactions within the clusters. Cluster-specific excitation spectra have been generated by monitoring the partial ion yields of the product cations. Resonance transitions of O1s (C==O/OH) electrons into π CO* orbital in the preedge region were found to shift in energy upon clusterization. A blueshift of the O1s (C==O) → π CO* transition by ∼0.2 eV and a redshift of the O1s (OH) → π CO* by ∼0.6 eV were observed, indicative of strong hydrogen-bond formation within the clusters. The results have been compared with a recent theoretical calculation, which supports the conclusion that the formic-acid clusters consist of the most stable cyclic dimer andor trimer units. Specifically labeled formic acid- d, HCOOD, was also used to examine the core-excited fragmentation mechanisms. These deuterium-labeled experiments showed that HD O+ was formed via site-specific migration of a formyl hydrogen within an individual molecule, and that H D2 O+ was produced via the subsequent transfer of a deuterium atom from the hydroxyl group of a nearest-neighbor molecule within a cationic cluster. Deuteron (proton) transfer from the hydroxyl site of a hydrogen-bond partner was also found to take place, producing deuteronated HCOOD D+ (protonated HCOOH H+) cations within the clusters.
journal title
Journal of Chemical Physics
volume
Volume 125
issue
Issue 19
start page
194307-1
end page
194307-10
date of issued
2006-11-16
publisher
American Institute of Physics
issn
0021-9606
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
publisher
rights
Copyright (c) 2006 American Institute of Physics.
relation url
department
Graduate School of Science