A spectroscopic study on the satellite vibronic band in phosphorescent Pt-complexes with high colour purity

The major origin of the satellite vibration band in emission spectra is the stretching of the terminal groups, which can be confirmed by IR and Raman spectroscopic techniques.

Aqueous Dispersion and Temperature Induced Reversible Fluorescence Properties of 1-Pyrenecarboxaldehyde

The fluorescence intensities for various vibronic fine structures in the 1-pyrenecarboxaldehyde (PyCHO) fluorescence show strong environment dependence. In aqueous solvent, the distribution of dye is highly depended on its concentration labels and varies from excimer to monomeric state. UV-Vis Spectroscopic analysis could not able to detect dye below 10-7M concentration, whereas a new monomeric peak at 342 nm was observed after heating and cooling treatment at above the concentration. At 10-8M concentration, only monomeric distribution of 1-PyCHO reveals a strong temperature (20-50 °C) induced reversible perturbation of the vibronic band intensities. This suggests the operation of some specific solute-solvent dipole-dipole interaction mechanism strongly influenced by heating.

Rotational Energy Distributions of Benzene Liberated from Aqueous Liquid Microjets: A Comparison between Evaporation and Infrared Desorption

We have measured the rotational energy distribution of benzene molecules both evaporated and desorbed by an IR laser from a liquid microjet. Analysis of the 601 vibronic band of benzene has shown that the benzene molecules evaporating from the liquid microjet surface have a rotational temperature of 157 ± 7 K. In contrast, the rotational temperature of benzene molecules desorbed from the liquid microjet by a 1.9 μm laser pulse is 82 ± 5 K. However, in both cases careful inspection of the spectral profiles shows that the experimental rotational distributions are non-Boltzmann, displaying an underpopulation of high rotational states and a relative overpopulation of the low rotational states. The non-equilibrium evaporation and desorption spectral profiles are consistent with a model that involves transfer of internal energy into translation upon liberation from the condensed phase.

Spectral Comparison of the Binding of Pyrene to β-Cyclodextrin and β-Cyclodextrin Derivatives

β-Cyclodextrin (β-CD) is a seven-unit cyclic sugar molecule with a torroidal shape, a hydrophilic exterior, and a hydrophobic cavity. It has been hypothesized that pyrene (P) forms a P(β-CD)2 complex in which the pyrene lies in between the two wide, or secondary, rims of the two β-CDs. This dimer structure appears to be stabilized in the crystal state by hydrogen bonds between –OH groups on the rims of the adjacent β-CDs. We have chosen to test this hypothesis by comparing the fluorescence properties of pyrene in the presence of substituted β-CDs with these properties in the presence of β-CD. These properties include the shape (I/III vibronic band ratio) and lifetime of pyrene fluorescence and the effect on the pyrene I/III ratio of additives such as an iodide ion and a fluorinated alcohol. The CD derivatives in this investigation include those with no wide rim substitution and those with substitution on both the wide and narrow rims of β-CD. Our data indicate that the a P(β-CD)2 complex forms only when there is no substitution on the wide rim, which confirms the proposed structure for this complex.

Laser Ionisation Spectroscopy Of Formyl Fluoride

A vibronic band of formyl fluoride near 39,511 cm-1 has been observed using multiphoton ionisation spectroscopy. From the analysis of the partially resolved rotational structure, the rotational parameters of the (0, 2, 0, 0, 0, 0) vibrational level of an electronic state near 39,000 cm ~1 have been determined: A = 92.50(1.46) GHz and (B + C)/2 = 11.23(30) GHz. The term value was determined to be 39,510.93(30) cm-1 .