Related Experiment Video
Updated: Aug 14, 2026

Characterization of Biological Absorption Spectra Spanning the Visible to the Short-Wave Infrared
Published on: January 10, 2025
Isomers of NCO2: IR-absorption spectra of ONCO in solid Ne
1Department of Chemistry, National Tsing Hua University, 101, Sec. 2, Kuang Fu Road, Hsinchu 30013, Taiwan.
Abstract:
Irradiation of a Ne matrix sample containing NO and CO near 4 K with an ArF excimer laser at 193 nm yielded new lines at 2045.1 and 968.0 cm(-1) that were depleted upon secondary photolysis at 308 nm. These lines are assigned to C=O stretching and mixed stretching modes of ONCO, based on results of 15N-, 13C-, and 18O-isotopic experiments and quantum-chemical calculations. These calculations using density-functional theory (B3LYP and PW91PW91/aug-cc-pVTZ) predict five stable isomers of NCO2: ONCO, NCOO, N-cyc-CO2, CNOO, and cyc-CNOO, listed in order of increasing energy. According to B3LYP calculations, ONCO has a trans configuration, with bond angles of angleONC approximately 136.3 degrees and angleNOC approximately 160.7 degrees. Calculated vibrational wave numbers, IR intensities, 15N-, 13C-, and 18O-isotopic shifts for ONCO agree satisfactorily with experimental results. ONCO was formed from reaction of CO with NO in its excited state.
Related Concept Videos
Molecular Spectroscopy: Absorption and Emission
IR Absorption Frequency: Hybridization
Among the sp, sp2, and sp3 hybridized orbitals, sp orbitals have the maximum s character (50%). Consequently, the electrons are held more closely to the nucleus, resulting in stronger and shorter C–H bonds that stretch at a...
Absorption of Radiation
IR Spectroscopy: Molecular Vibration Overview
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
UV–Vis Spectroscopy: Molecular Electronic Transitions
IR Spectrometers

