Department of Chemistry and Research Institute of Natural Science, Gyeongsang National University, Jinju , Republic of Korea.
Phys Chem Chem Phys. 2011 Oct 6;13(37):16537-41. doi: 10.1039/c1cp21999e. Epub 2011 Aug 18.
The conformational structures of jet-cooled acetaminophen were investigated in the gas phase by resonant 2-photon ionization and UV-UV hole-burning spectroscopy. In contrast to the results from a previous study, two nearly isoenergetic conformers were distinctly found in a supersonic molecular beam expansion and positively identified as the cis and trans isomers of acetaminophen by UV-UV hole-burning spectroscopy. The 0-0 bands of the cis and trans isomers were found at 33518.7 and 33485.6 cm(-1), respectively. The vibronic bands of the two isomers are close-lying and/or partially overlapping due to the small energy difference (33 cm(-1)) between the two 0-0 bands. As a consequence, the recorded resonant 2-photon ionization spectrum is highly congested in the low excitation energy region, which develops continuously into a featureless, broadened spectrum in the high energy region.
采用共振双光子电离和紫外-紫外光烧孔光谱法，在气相条件下研究了射流冷却对乙酰氨基酚的构象结构。与之前研究的结果不同，在超声分子束扩展中明显发现了两个几乎等能量的构象体，并通过紫外-紫外光烧孔光谱法将其确认为对乙酰氨基酚的顺式和反式异构体。顺式和反式异构体的 0-0 带分别位于 33518.7 和 33485.6 cm(-1)。由于两个 0-0 带之间的能量差（33 cm(-1))很小，两个异构体的振子带非常接近/部分重叠。因此，在低激发能量区域，记录的共振双光子电离光谱高度拥挤，在高能区域连续发展为无特征、展宽的光谱。
