In situ monitoring of the growth of ice films by laser picosecond acoustics

Abstract

Ultrashort optical pulses are used to excite and probe picosecond acoustic pulses in a sample consisting of an opaque material upon which ice is continuously deposited from the vapor phase at ϳ110 K. By analysis of the ultrasonic propagation and reflection inside the submicron ice film and taking into account the scattering of the probe light by the acoustic waves, the thickness, sound velocity, refractive index, ultrasonic attenuation, and photoelastic constant of the ice film are derived. This method should find applications for the in situ monitoring of thin transparent films during growth.

Coherent shear phonon generation and detection with picosecond laser acoustics

“…͑These estimates are a little smaller than the experimental durations because of the effects of the ultrasonic absorption, and one should bear in mind that they are only order-of-magnitude estimates.͒ For the case of no ultrafast diffusion ͑g = ϱ or =0͒, the echoes become unreasonably short ͑as is clear from Fig. 5͒ 30+ 60i Zn, P 12 9−40i Zn, P 13 27− 38i Zn, P 31 100− 200i Zn, P 33 200+ 300i Zn, P 44 120+ 150i Electron-phonon coupling constant of Zn g ͑Wm…”

“…This f 2 attenuation is also included in the time-domain simulation. 44 The ultrasonic attenuation in the Zn is negligible for the small acoustic penetration distances experimentally probed ͑i.e., the optical penetration depth͒ and is not included. Figure 5 shows the calculated strain distribution at 100 ps after the pump light pulse arrival.…”

Nanoscale mechanical contacts probed with ultrashort acoustic and thermal waves

“…At t = 0 we observe a peak followed by a dip and then a rise in ͉␦R / R 0 ͉ at t = 10-20 ps. This is due to the cumulative effects of a transient-temperature rise 17 …”

Ultrafast ellipsometric interferometry for direct detection of coherent phonon strain pulse profiles

“…This attenuation is also included in the simulation of the propagation of the coherent phonon pulses. The detailed procedure is described elsewhere [54]. Once η zz z; t is obtained, Eqs.…”