Phonon spectroscopy

Wybourne, M. N.; Wigmore, J. K.

doi:10.1088/0034-4885/51/7/001

Cited by 53 publications

(24 citation statements)

References 264 publications

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“…In particular this may be achieved by high-frequency phonon excitation and detection, providing a wealth of information on the elastic properties of solids on nanometer and atomic length scales owing to the enhancement in scattering when the phonon wavelength is of the same order as the structure under investigation. This field of research, initially driven by terahertz phonon measurements involving superconducting tunnel junctions, heat pulses, phonon-induced fluorescence, and Raman or Brillouin scattering [1,2], has more recently been supplemented with ultrafast optical techniques in the time domain. In particular, such impulsive optical generation and delayedtime optical probe detection at surfaces permits the use of propagating GHz-THz phonon pulses to acoustically inspect the interior of nanostructures [3][4][5][6][7][8][9][10].…”

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Coherent Shear Phonon Generation and Detection with Ultrashort Optical Pulses

et al. 2004

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Using an optical technique we generate and detect picosecond shear and quasishear coherent acoustic phonon pulses in the time domain. Thermoelastic and piezoelectric generation are directly achieved by breaking the sample lateral symmetry using crystalline anisotropy. We demonstrate efficient detection in isotropic and anisotropic media with various optical incidence geometries. DOI: 10.1103/PhysRevLett.93.095501 PACS numbers: 63.20.Dj, 43.35.+d, 78.20.Hp, 78.47.+p By shaking atoms one may assess interatomic bond strengths and the integrity of crystal lattices. In particular this may be achieved by high-frequency phonon excitation and detection, providing a wealth of information on the elastic properties of solids on nanometer and atomic length scales owing to the enhancement in scattering when the phonon wavelength is of the same order as the structure under investigation. This field of research, initially driven by terahertz phonon measurements involving superconducting tunnel junctions, heat pulses, phonon-induced fluorescence, and Raman or Brillouin scattering [1,2], has more recently been supplemented with ultrafast optical techniques in the time domain. In particular, such impulsive optical generation and delayedtime optical probe detection at surfaces permits the use of propagating GHz-THz phonon pulses to acoustically inspect the interior of nanostructures [3][4][5][6][7][8][9][10]. Acoustic phonon generation with ultrashort optical pulses is enabled by a variety of mechanisms, such as themoelasticity [3][4][5][6][7][8][9], deformation potential coupling [10,11], or screening of electric fields combined with piezoelectricity [12,13]. The respective excitation of thermal phonons, carriers, or (rapid changes in) screening potential in an opaque material produce an initial stressed near-surface region whose size in the lateral direction ( * 1 m) depends on the optical spot diameter and in the depth direction ( & 100 nm) on optical absorption, carrier diffusion or builtin electric field localization. Phonon detection is achieved through the photoelastic effect or surface displacement when the phonon pulse returns to the same point on the surface after scattering within a short distance. In this case, with isotropic media or symmetrically cut crystals, the constraints of symmetry imply that one only excites longitudinal acoustic phonons in the depth direction.Such longitudinal acoustic phonon experiments have lead to picosecond time-scale studies involving as diverse a range of subjects as ultrashort time-scale carrier diffusion in metals and semiconductors [5,9,10], highfrequency ultrasonic attenuation in crystals and glasses [14,15], phonon generation and detection in semiconductor quantum wells and superlattices [6,12,16], and soliton propagation and their coupling to two-level systems in ruby [7,17]. In spite of these successes, these experiments only address one of the three acoustic polarizations. To match the impressive capabilities of Brillouin and Raman scattering techniques one would naturally w...

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Coherent Shear Phonon Generation and Detection with Ultrashort Optical Pulses

et al. 2004

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“…Although experiments on nonequilibrium phonons in crystals have proven to give a wealth of information on elementary phonon scattering processes [9], the number of dynamical experiments investigating high-frequency (n ¿ 1 THz) vibrations in noncrystalline solids is quite limited. Pulsed Raman spectroscopy has been used to examine phononlike modes in a-Si(:H) [10].…”

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Dynamics of Si-H Vibrations in an Amorphous Environment

et al. 2000

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We present results of the first vibrational photon-echo, transient-grating, and temperature dependent transient-bleaching experiments on a-Si:H. Using these techniques, and the infrared light of a free electron laser, the vibrational population decay and phase relaxation of the Si-H stretching mode were investigated. Careful analysis of the data indicates that the vibrational energy relaxes directly into Si-H bending modes and Si phonons, with a distribution of rates determined by the amorphous host. Conversely, the pure dephasing appears to be single exponential, and can be modeled by dephasing via two-phonon interactions.

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“…The phonons are generated as heat pulses via standard techniques [4]. Those having energy greater than 2∆, the energy gap of the superconductor, are absorbed in the STJ, and because the phonon flux is uniform and absorption effectively instantaneous and uniform the resulting qp density is laterally homogeneous.…”

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Quasiparticle dynamics in a tantalum superconducting tunnel junction photon detector studied using phonon pulses

Wigmore¹,

Boyd²,

Kozorezov³

et al. 2004

phys. stat. sol. (c)

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PACS 74.25. Kc, 85.25.Oj We have used non-equilibrium phonon pulses to mimic X-ray photon absorption in a high quality Ta superconducting tunnel junction at 20 mK. From pulse shape measurements the charge output and decay time were determined. Values obtained were in good agreement with those obtained by photo-absorption after allowance for loss due to flux trapping. Results obtained for the quasiparticle loss rate due to Abrikosov vortices (fluxoids) were compared with the trapping model of Golubov and Houwman. Comparison of Ta and Nb results suggest that at very low temperatures fluxoid trapping may result in enhanced tunnelling rather than extra loss.

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Phonon spectroscopy

Cited by 53 publications

References 264 publications

Coherent Shear Phonon Generation and Detection with Ultrashort Optical Pulses

Coherent Shear Phonon Generation and Detection with Ultrashort Optical Pulses

Dynamics of Si-H Vibrations in an Amorphous Environment

Quasiparticle dynamics in a tantalum superconducting tunnel junction photon detector studied using phonon pulses

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