IR spectra of protonated benzaldehyde clusters, C7H7O+-Ln (L=Ar, N2; n!2):
Ion-ligand binding motifs of the cis and trans oxonium isomers
Shamik Chakraborty, Alexander Patzer, Otto Dopfer*
Institut für Optik und Atomare Physik, Technische Universität Berlin,
Hardenbergstrasse 36, 10623 Berlin, Germany
* corresponding author: dopfer@physik.tu-berlin.de, Fax: (+49) 30-31423018
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Figure S1. Mass spectra obtained by mass selecting BZH+-Ar (m=147 u) with the first quadrupole and
scanning the second quadrupole with no laser excitation (a), with resonant IR excitation at !IR=3476 cm-1 (b),
and with 10-5 mbar of N2 gas into the octopole (c). BZH+ ions (m=107 u) in spectrum (a) originate from
metastable decay. Spectra (b) and (c) show additional signals in the BZH+ mass channel arising from laserinduced (LID) and collision-induced dissociation (CID), respectively.
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Figure S2. Mass spectra obtained by mass selecting BZH+ (m=107 u) with the first quadrupole and scanning
the second quadrupole with no laser excitation (a), with resonant IR excitation at !IR=3555 cm-1 (b), and with
10-5 mbar of N2 gas into the octopole (c). C6H7+ fragment ions+ ions (m=79 u) in spectrum (a) originate from
metastable decay (MD). Spectra (b) and (c) show additional signals in the C6H7+ mass channel arising from
laser-induced (LID) and collision-induced dissociation (CID), respectively.
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Figure S3. IRPD spectra of (a) benzaldehydeH+-Ar (present work), (b) phenol+-Ar (Ref. [1]), and (c)
phenolH+-Ar (oxonium isomer, Ref. [2]), showing the O-H stretch bands of H-bonded and !-bonded isomers.
The spectra are shifted to the red by 3456 (a), 3463 (b), and 3328 (c) cm-1 in order to directly compare the
band shapes. The spectrum (d) is obtained by adding two phenol+-Ar spectra (b) with equal weight and
displaced by 20 cm-1 in order to simulate a spectrum of two isomers with an H-bonded and !-bonded isomer
each and a splitting of 20 cm-1 in the monomer frequency. As can be seen, spectrum (d) is very similar in
appearance to spectrum (a) supporting the conclusion that both spectra are generated by in total 4 isomers
(2 H-bonded and 2 !-bonded ones).
[1] N. Solca and O. Dopfer, Chem. Phys. Lett. 325 (2000) 354.
[2] N. Solca and O. Dopfer, J. Am. Chem. Soc. 126 (2004) 1716.
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