title: Conformationally resolved spectra of acetaminophen by UV-UV hole burning and IR dip spectroscopy in the gas phase.
abstract: Electronic and vibrational spectra of acetaminophen were measured by using UV-UV hole burning (HB) and IR dip spectroscopy. HB spectra show the coexistence of 4 different species, which include two new ones. Low-frequency transitions in the spectra are reproduced by a one-dimensional periodic potential with a free-rotor basis set for the methyl group. From the analysis, we concluded that acetaminophen has two conformers and each conformer gives two independent transitions starting from the most stable 0a(1) and the hot 1e internal rotational levels. It is also found that the HB spectrum of the trans-conformer in the previous report is that from the 1e excited level, while the HB spectrum of the cis-conformer is contaminated by the transitions of the trans-conformer. Potential curves of the methyl rotational motion are determined both in S(0) and S(1).
authors.affiliation: Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Woon Yong
authors.initials: WY
authors.lastname: Sohn
authors.forename: Shun-ichi
authors.initials: S
authors.lastname: Ishiuchi
authors.forename: Mitsuhiko
authors.initials: M
authors.lastname: Miyazaki
authors.forename: Jeongseok
authors.initials: J
authors.lastname: Kang
authors.forename: Soyoung
authors.initials: S
authors.lastname: Lee
authors.forename: Ahreum
authors.initials: A
authors.lastname: Min
authors.forename: Myong Yong
authors.initials: MY
authors.lastname: Choi
authors.forename: Hyuk
authors.initials: H
authors.lastname: Kang
authors.forename: Masaaki
authors.initials: M
authors.lastname: Fujii
mesh_terms: D000082:Acetaminophen / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013816:Thermodynamics; D014466:Ultraviolet Rays
chemical_list: D005740:Gases; D000082:Acetaminophen