GFP-related chromophores: photoisomerization, thermal reversion, and DNA labelling.

Due to the pronounced effect of the confined environment on the photochemical properties of 4-hydroxybenzylidene imidazolinone (HBI), a GFP-related chromophore, imidazolidinone and imidazothiazolone analogues have been studied as fluorescent probes. Their photoisomerization and their thermal reversion were studied under 365-nm-irradiation, resulting in observation of an enthalpy-entropy compensation effect. Theoretical studies were carried out to shed light on the thermal reversion mechanism.

Time-resolved observations of vibrationally excited NO X Π (') formed from collisional quenching of NO A Σ ( = 0) by NO X Π: evidence for the participation of the NO a Π state.

Time-resolved observations have been made of the formation of vibrationally excited NO X Π (') following collisional quenching of NO A Σ ( = 0) by NO X Π ( = 0). Two time scales are observed, namely a fast production rate consistent with direct formation from the quenching of the electronically excited NO A state, together with a slow component, the magnitude and rate of formation of which depend upon NO pressure. A reservoir state formed by quenching of NO A Σ ( = 0) is invoked to explain the observations, and the available evidence points to this state being the first electronically excited state of NO, a Π.

Infrared Emission from Photodissociation of Methyl Formate [HC(O)OCH] at 248 and 193 nm: Absence of Roaming Signature.

Following photodissociation at 248 nm of gaseous methyl formate (HC(O)OCH, 0.73 Torr) and Ar (0.14 Torr), temporally resolved vibration-rotational emission spectra of highly internally excited CO (ν ≤ 11, ≤ 27) in the 1850-2250 cm region were recorded with a step-scan Fourier-transform spectrometer.