The invention of holography by Denis Gabor2 in 1948 initiated a new direction in information recording.However, because of limitations such as unavailability of coherent light sources, holography lay dormant for almost a decade.The discovery of the off-axis holographic technique by Leith and Upatneiks2in 1962 and the development of highly coherent laser sources created waves of excitement and a resurgence in the field of holography.Simultaneously, Denisyuk’s3and Van Heerdeen’s4proposal of Lippman holography and deep (volume) holograms at the same period gave a new life to the domain of holography.The reconstructed three-dimensional images seen through a hologram struck the imagination of scientists all over the world and there was a burst of research activity to find new recording materials and techniques capable of recording the complete optical information carried by object wavefronts5-13The demand for better materials with stringent characteristics such as high resolution, better energy sensitivity, broad wavelength sensitivity, simpler processing procedure, and erasability was severely felt and still exists today.

Holographic Recording Materials

We observe fluorescence excitation lines of single terrylene molecules in three new polymer matrices (polyvinylbutyral, polymethylmethacrylate, and polystyrene) and in two crystals, n‐hexadecane (polycrystalline Shpol’skii matrix) and anthracene single crystal. We also burn persistent spectral holes in bulk samples of these solutions for comparison to single molecule lines. In all matrices where hole burning is efficient enough, we find good agreement between the average width determined from the distribution of single molecules’ linewidths and the homogeneous width deduced from spectral holes, which demonstrates the consistency and complementarity of the two techniques.

Single molecule lines and spectral hole burning of terrylene in different matrices

Tautomeric equilibria (mainly of the lactam-lactim type) for a rather large number of six-membered heterocyclic molecules are calculated by the semiempirical AM1, MNDO-PM3, and MNDO methods. Except for compounds with adjacent pyridine-like lone pairs both AM1 as well as MNDO-PM3 give rather reliable predictions for relative stabilities of the various tautomeric species–comparable to quite high level ab initio calculations. The known errors associated with MNDO in the treatment of heterocyclic tautomerism are thus largely corrected in AM1 as well as MNDO-PM3. For 2-hydroxypyridine-pyrid-2(1H)-one the effect of self-association is less satisfactorily described by MNDO-PM3 than by AM1. MNDO-PM3 calculated relative stabilities of methylated derivatives are, however, in considerably closer agreement with experimental values than those obtained by AM1. Ionization potentials, especially those for lone-pair orbitals, are overestimated by all three semiempirical methods. MNDO-PM3 results for nitrogen lone-pair orbital energies are slightly better than those obtained by the AM1 or MNDO method.

Tautomeric equilibria of heterocyclic molecules.: a test of the semiempirical AM1 and MNDO-PM3 methods

Holographic detection is compared with the more common transmission method. The signal shapes of the optical holes determined by both techniques are studied theoretically and experimentally as a function of the burning fluence. From a comparison of the transmission signals and the holographic signals, the homogeneous linewidth can be determined. Experimental data was obtained from free base chlorin (1,2‐dihydroporphyrin) in a polyvinylbutyral film at a temperature of 1.7 K. From these measurements a homogeneous linewidth of 350 MHz was determined. Limits of sensitivity of the holographic detection method are discussed.

Spectral hole‐burning and holography. I. Transmission and holographic detection of spectral holes

Solute-solvent dynamics and interactions in glassy media: Photon echo and optical hole burning studies of cresyl violet in ethanol glass

Hole-burning spectroscopy in dye-doped polymers by spatial modulation technique

Time evolution of a persistent hole spectrum has been investigated for dyes doped in polyvinyl alcohol films at 2 K. The zero‐phonon hole profile measured for resorufin using a single‐mode dye laser has been found to be nearly Lorentzian even in the case of relatively deep holes. The observed fluence‐dependent depth and width of the zero‐phonon hole are reproduced well by the numerical simulation based on a dispersive burning‐kinetics model. It is pointed out that a large distribution of the burning rate is responsible for the fluence‐dependent hole broadening. Time evolution of the phonon‐sideband hole simulated using the same model is also compared with the experimental data. It is shown that the low‐energy sideband hole is enhanced when the burning kinetics is dispersive.

R. Shiraishi

Papers

Hole-burning spectroscopy in dye-doped polymers by spatial modulation technique

Time dependence of hole spectrum due to dispersive burning kinetics in dye‐doped polymers

Effects of dispersive burning kinetics on hole-burning spectrum in dye-doped polymers