Photochemical hole burning of phthalocyanine in polymer glasses: Thermal cycling and spectral diffusion

Abstract

Twolevel systems and lowtemperature glass dynamics: Spectral diffusion and thermal reversibility of hole burning linewidths J. Chem. Phys. 92, 4145 (1990); 10.1063/1.457773Photochemical hole burning of 1,4dihydroxyanthraquinone in polymer glasses: Poly(ethylene), poly(methacrylic acid), and their copolymer systems ~n this ~aper we report an analysis of hole burning line shapes yielding both reversible and lrreVerSl?le contributions to the linewidth which are due to spectral diffusion. These terms show a lInear T dependence and can, through cycling experiments, be investigated in the temperature range of 0.5 < ~ -:: 25 K. The range 1 < T < 25 K is particularly interesting because, under normal condItIons, Debye contributions and local mode contributions overwhelm the small spectral diffusion terms at these temperatures. Comparison between optical data and specific heat data supports our model of spectral diffusion.

Isotope effect in the linewidth distribution of single-molecule spectra in doped toluene at 2K

“…The width of individual spectral peaks caused by the interaction with one vibrational mode can then approximately be expressed as (e.g., Refs. [19,23])…”

Dynamics of amorphous polymers in the temperature region 2– where the standard model of low-temperature glasses begin to fail: studies by single molecule spectroscopy and comparison with photon echo data

“…One usually takes into account the interaction of the chromophores with one or two LFMs with energies in the range 10-30 cm À1 [51,52]. The contribution of a LFM with energy DE to the homogeneous line width, G LFM ; is given by [52] …”

“…First consideration of this contribution, took into account only one or two discrete LFMs with frequencies in the range 10-30 cm À1 (in analogy with the case of mixed crystals) (see, for example, Refs. [19,20]). However, the low-frequency inelastic light scattering and the inelastic neutron scattering experiments, which provide information about the spectrum of LFMs, have not confirmed the presence of such discrete modes.…”

Vibrational dynamics of glasses at low temperatures: Investigation by single-molecule spectroscopy

“…In a perfect crystal doped by chromophore molecules the interaction of a given SM with one LFM leads to the following dependence of its line width, DG LFM (T), on T [29]:…”