Kasha or state selective behavior in the photochemistry of ortho-nitrobenzaldehyde?Electronic supplementary information (ESI) available. See DOI: 10.1039/c2pp25057h

The photochemistry of ortho -nitrobenzaldehyde dissolved in tetrahydrofuran was studied by means of femtosecond UV/Vis and IR spectroscopy. Comparison was made of the spectral and temporal signatures for 400 nm and 260 nm excitation. The 400 nm excitation promotes NBA to its lowest excited singlet s...

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Bibliographic Details
Main Authors: Schmierer, T, Ryseck, G, Villnow, T, Regner, N, Gilch, P
Format: Article
Language:English
Online Access:Get full text
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Summary:The photochemistry of ortho -nitrobenzaldehyde dissolved in tetrahydrofuran was studied by means of femtosecond UV/Vis and IR spectroscopy. Comparison was made of the spectral and temporal signatures for 400 nm and 260 nm excitation. The 400 nm excitation promotes NBA to its lowest excited singlet state of n* character whereas for 260 nm an upper excited state of * character is addressed. On the picosecond time scale, the molecule undergoes hydrogen transfer, yielding a ketene intermediate, internal conversion recovering the starting material, and intersystem crossing. Time constants and yields of these processes are virtually not affected by the excitation wavelength. For 400 nm excitation a 100 fs decay component seen in the 260 nm experiment is absent, indicating that this component is due to a * n* internal conversion. In contrast to its formation, the decay of the ketene intermediate is influenced by the excitation wavelength. This can be attributed to different amounts of vibrational excitation. The title compound undergoes ultrafast hydrogen transfer upon photo absorption. Femtosecond spectroscopy shows that yields and time constants of this process are virtually not affected when tuning the excitation wavelength over a broad range.
ISSN:1474-905X
1474-9092
DOI:10.1039/c2pp25057h