Studies of Nonequilibrium Phonons by Optical Techniques

Renk, K. F.

doi:10.1007/978-1-4613-2501-7_2

Cited by 5 publications

(5 citation statements)

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“…Bron and Grill (1977) reported an w 2 frequency dependence for the point defect scattering by Eu2+ in SrFz, measured with the vibronic sideband spectrometer. On the same material at a slightly different concentration, Eisfeld and Renk (1979) using phonon induced fluorescence (data reanalysed by Renk (1985)) found a dependence closer to w4. These data illustrate the difficulty of isolating point defect scattering from other effects.…”

Section: Scattering By Point Defectsmentioning

confidence: 95%

“…Both optic and acoustic modes may be studied, though we shall restrict our discussion to acoustic phonons. A comprehensive review of this area has been given by Renk (1985).…”

Section: Optical Techniquesmentioning

confidence: 99%

“…Before the inception of the CaF2 : Euz+ stress spectrometer, many experiments were carried out in ruby, using phonons generated and detected by similar techniques but at a fixed frequency of 874 GHz (29 cm-I). The relevant energy levels of A1203:Cr3+ are given by Renk (1985). To generate 29 cm-I phonons, the 2A and levels may be pumped via the higher green and blue absorption bands using any one of a variety of sources, for example, a c w lamp (Renk and Deisenhofer 1971), c w argon ion laser (Dijkhuis et a1 1976) or pulsed dye laser (Meltzer and Rives 1977).…”

Section: Optical Techniquesmentioning

confidence: 99%

“…For example, 40 cm-' phonons resonant with the optically excited states of Cr3+ in alexandrite (BeAI,O,) have been studied by Goossens et a1 (1984) while optically excited Cr3' centres in yttrium aluminium garnet (Y3A15012) generate 19.5cm-' resonant phonons (Goossens et a1 1985b). The review by Renk (1985) encompasses a complete and up-to-date bibliography.…”

Section: Optical Techniquesmentioning

confidence: 99%

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Phonon spectroscopy

Wybourne¹,

Wigmore²

1988

Rep. Prog. Phys.

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Rapid progress has taken place in phonon spectroscopy since the review by Bron in 1980. We restrict ourselves to acoustic branch phonons, and describe the improvements in technique that make it now possible to study phonons in some materials right up to the Brillouin zone edge. Major advances have taken place particularly in the areas of phonon imaging and in the use of superconducting tunnel junctions. It is observed that the transport of high-frequency phonons is influenced strongly by focusing effects due to crystal anisotropy. In the context of the electron-phonon interaction, we describe the scattering and emission of phonons by bound and free electrons. Another area of great interest relates to the scattering of phonons at boundaries and interfaces, and their connection with disordered systems and other structural defects.

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Section: Scattering By Point Defectsmentioning

confidence: 95%

“…Both optic and acoustic modes may be studied, though we shall restrict our discussion to acoustic phonons. A comprehensive review of this area has been given by Renk (1985).…”

Section: Optical Techniquesmentioning

confidence: 99%

Section: Optical Techniquesmentioning

confidence: 99%

Section: Optical Techniquesmentioning

confidence: 99%

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Phonon spectroscopy

Wybourne¹,

Wigmore²

1988

Rep. Prog. Phys.

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“…It is interesting to compare this estimation with an estimation of absorption cross section by a resonant two-level absorber. This cross section is of the order of 10 212 cm 2 (see, for example, [29]). But if the interaction cross section of high-energy phonons with DWPs would be as high as 10 212 cm 2 , high-resolution optical measurements would be impossible in glasses at low temperatures not only for the case of SMS, but also for photon echo and hole burning experiments due to a huge amount of light induced SD.…”

mentioning

confidence: 99%

Electronic Energy Relaxation and Transition Frequency Jumps of Single Molecules at 30 mK

Plakhotnik

Donley²,

Kharlamov³

2001

Phys. Rev. Lett.

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Transition frequency jumps for single terrylene molecules in a polyethylene matrix caused by resonant laser irradiation are investigated at 30 mK. These jumps are not accompanied by substantial sample heating. A model for the effect is proposed, based on the interaction of tunneling two-level systems (TLSs) surrounding the single molecule with high-energy nonthermal phonons emitted by the molecule during electronic energy relaxation. The radius of the effective interaction volume is estimated to be r m ഠ 12.5 nm, and the interaction cross section for nonequilibrium phonon -TLS scattering is estimated as ϳ10 222 cm 2 . DOI: 10.1103/PhysRevLett.87.015504 PACS numbers: 61.43.Fs, 78.40. -q The low-temperature properties of glasses have strong anomalies as compared to crystals [1][2][3]. These anomalies are successfully described by the tunneling two-level system (TLS) model, which assumes the existence of a special kind of local low-energy excitations with a very broad distribution of energies and relaxation rates. Phonon assisted TLS dynamics is thought to be responsible for many anomalous properties of glasses at low temperatures and has been the subject of extensive investigation by various methods for almost 30 years. One tool used for the investigation of these dynamics is optical spectroscopy, in particular, photon echo, hole burning, and single-molecule spectroscopy (SMS) (see reviews [4 -13]). All of these methods use a chromophore impurity as a probe whose resonance frequency is subject to spectral diffusion (SD) because of interactions between the probe and TLSs. In principle, impurities can disturb the matrix structure, but there is no indication that impurities at low and moderate concentrations affect the TLS density. An increase of the rate of SD has been detected in samples only at chromophore concentrations above 10 22 mol͞l [14]. Another expected effect of impurity molecules on their local environments could arise from light absorbed by the chromophore. Through subsequent decay processes the absorbed energy is inevitably partially converted to high-energy phonons, which spread into the surrounding space, exciting TLSs and finally decaying into thermal equilibrium phonons. TLS excitation via high-energy phonons was suggested in [14] as a reason for a specific SD time dependence in highly concentrated samples, but no direct evidence for this effect was obtained. The advantage of SMS in measurements of such a kind is that one and the same molecule serves as a phonon generator and as a probe. Therefore, the measurements can be carried out at a low concentration of chromophores, which does not disturb the structure of the matrix. The present work is a first attempt at direct investigation of the influence of highenergy phonons emitted by impurity molecules on their local environments.Experiments were performed on the sample used in previous works [15,16]. The sample has a sandwich structure. A thin layer (about 1 mm thick) of polyethylene (PE) doped with terrylene at a concentration of ϳ10 26 M was p...

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Heat‐Pulse Propagation in Solids

Narayanamurti

2003

Digital Encyclopedia of Applied Physics

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Studies of Nonequilibrium Phonons by Optical Techniques

Cited by 5 publications

References 59 publications

Phonon spectroscopy

Phonon spectroscopy

Electronic Energy Relaxation and Transition Frequency Jumps of Single Molecules at 30 mK

Heat‐Pulse Propagation in Solids

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