Hole-burning Experiments Research Articles

Phonon selective low temperature photochemistry in alcohol glasses

The molecule dihydroxyanthraquinone, which exhibits reversible, light-induced proton transfer is chosen for photo-chemical hole burning experiments in alcohol glasses. The experiments show the novel feature of a phonon selective photo-chemical mechanism, which verifies experimentally that the different sites in glasses have rather large variations in electron-phonon coupling strength.

Spectral diffusion in acceptor-hole system in germanium at low temperature: ultrasonic hole-burning experiment

The interaction among lightly doped acceptors in germanium is observed by an ultrasonic hole-burning experiment. The observed width of the burned hole is ascribed to spectral diffusion due to the exchange and quadrupole interactions of nearest-neighbour acceptor pairs. In a strong magnetic field the exchange interaction is suppressed and hence the width is due to the quadrupole interaction and the single-phonon relaxation process (2T1)-1.

Photophysical and photochemical molecular hole burning theory

In this paper theories are given, describing photophysical and photochemical hole burning experiments on molecular mixed crystals at low temperature. Population saturation hole burning is treated for a two-level system where the lower level is the ground state. Hole burning due to a triplet state acting as a population bottle neck is also described by a steady-state density matrix theory. Connection is made with optical free induction decay. To obtain T2 (the decay time of the off-diagonal elements of the density matrix), which is the main goal of these hole burning experiments, a linear extrapolation method is discussed. For photochemical hole burning a time-dependent density matrix treatment is given. Using this theory numerical simulations were performed of the experimental results obtained by Völker and co-workers for porphin in n-octane at low temperature. Good agreement with experiment is obtained. For this case extrapolation methods are discussed in order to obtain reliable T2 values. A time-dependent kinetic theory is used to simulate the photochemical hole burning experiments on dimethyl-s-tetrazine in durene and s-tetrazine in benzene. This theory accounts for the recently revealed two-photon character of these photodissociations. It is shown that despite this complication the hole full width at half-maximum may still equal twice the homogeneous width of the So-S1 transition.

Ir hole burning and line shape of matrix-isolated 1,2-difluoro-ethane with tunable diode lasers. part 2

Some recent results of IR hole burning experiments of CH2F-CH2F (trans conformation), matrix isolated in Ar and Kr are reported. A low power tunable diode laser was used for burning holes into the absorption profile as well as for recording the spectra. Temperature dependence of the hole width, closely related to the homogeneous width was determined, from which a vibrational life time of 5̃ ns at 0 K can be estimated. Effects of polarized laser radiation are demonstrated.

Optical detection of magnetic resonance in zero field on triplet excitons and localized states in pure and doped NaNO 2 single crystals

The first excited triplet state of NaNO 2 single crystals and crystals doped with 1% KNO 2 has been investigated using optically detected magnetic resonance in zero field. Three different triplet states could be distinguished: Mobile excitons, localized traps ( z) due to the dopant KNO 2 in the doped crystals and NaNO 2-traps. The corresponding zero-field splitting parameters are D exc = 0.45611 cm −1, E exc = −0.04779 cm −1, D z = 0.43570 cm −1 and E z = −0.04912 cm −1. For the NaNO 2-traps only the E-values can be given to have the respective values −0.04829 cm −1, −0.04873 cm −1, −0.04875 cm −1 and −0.05010 cm −1. Optically detected hole-burning experiments proved that the exciton ODMR-line is homogeneously broadened, whereas the trap signals are inhomogeneously broadened by second order hyperfine interaction with the 14N nucleus.