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Fine speciation of active sites in zeolites by a CO probe: Dynamics and IR frequencies
Author(s) -
Rejmak Paweł,
Datka Jerzy,
Broclawik Ewa
Publication year - 2018
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.25625
Subject(s) - zeolite , chemistry , molecular dynamics , adsorption , infrared spectroscopy , infrared , molecule , ab initio , molecular vibration , ab initio quantum chemistry methods , spectroscopy , computational chemistry , spectral line , chemical physics , molecular physics , catalysis , physics , optics , quantum mechanics , organic chemistry
The influence of system dynamics onto infrared spectra calculated and measured for probe molecules weakly interacting with active sites is discussed. OH stretching frequencies for Brønsted sites in Y zeolite and their shift on CO adsorption (measured by IR spectroscopy at ca. 170 K) are simulated from AIMD trajectory, based on BO DFT calculations. We present here very good agreement between experimental and computed OH frequency red‐shift on CO adsorption in dealuminated zeolite Y. It is shown that extracting nonharmonic OH frequencies from ab initio molecular dynamics trajectory provides better estimate of experimental IR results than standard vibrational analyses due to realistic computational model and better correspondence with experimental conditions.