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Your search keyword '"Harvey, N."' showing total 8 results
Start Over Author "Harvey, N." Publisher american institute of physics
8 results on '"Harvey, N."'

1. Optical second harmonic generation analysis of the atomically stepped Au/TiO_2 (320) interface

Author

Haque, Md Ehasanul, Kobayashi, Daiki, Tomatsu, Yuki, Hien, Khuat Thi Thu, Mizutani, Goro, Rahman, Mohammad Mizanur, Rutt, Harvey N., Haque, Md Ehasanul, Kobayashi, Daiki, Tomatsu, Yuki, Hien, Khuat Thi Thu, Mizutani, Goro, Rahman, Mohammad Mizanur, and Rutt, Harvey N.

Abstract

A gold thin film with the thickness of 2nm on the TiO_2(320) substrate has been fabricated in a UHV chamber at the pressure of 2x10^<-7> Torr. We observed the second harmonic response from the Au/TiO_2(320) interface and bare TiO_2(320) as a function of the rotation angle around the surface normal by using of a pulsed Nd^<3+>:YAG laser as the excitation light at a photon energy of 1.17 eV and 2.33 eV. An isotropic response was observed from both samples for 1.17 eV photon energy excitation. In contrast, an anisotropic response was observed from both samples for 2.33 eV photon energy excitation. From the Au/TiO_2(320) interface, anisotropic structure of SHG response was observed in the [2^^⎯30] direction for Pin/Pout polarization combination. Nonlinear susceptibility elements were decomposed and two groups of them were assigned as the main contribution from the step and terrace of the vicinal TiO_2 surface.

Published
2017

4. Optical second harmonic generation analysis of the atomically stepped Au/TiO2 (320) interface.

Author

Haque, Md Ehasanul, Daiki Kobayashi, Yuki Tomatsu, Khuat Thi Thu Hien, Goro Mizutani, Rahman, Mohammad Mizanur, and Rutt, Harvey N.

Subjects
SECOND harmonic generation, HARMONIC generation, ND-YAG lasers, HARMONIC analysis (Mathematics), LIGHT, GOLD films, PULSED lasers
Abstract

A gold thin film with the thickness of 2nm on the TiO2(320) substrate has been fabricated in a UHV chamber at the pressure of 2x10-7 Torr. We observed the second harmonic response from the Au/TiO2(320) interface and bare TiO2(320) as a function of the rotation angle around the surface normal by using of a pulsed Nd3+:YAG laser as the excitation light at a photon energy of 1.17 eV and 2.33 eV. An isotropic response was observed from both samples for 1.17 eV photon energy excitation. In contrast, an anisotropic response was observed from both samples for 2.33 eV photon energy excitation. From the Au/TiO2(320) interface, anisotropic structure of SHG response was observed in the [¯230] direction for Pin/Pout polarization combination. Nonlinear susceptibility elements were decomposed and two groups of them were assigned as the main contribution from the step and terrace of the vicinal TiO2 surface. [ABSTRACT FROM AUTHOR]

Published
2017
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5. Gas Sensor Design Using a Fabry-Perot Interferometer and a Pyroelectric Detector.

Author

Vargas-Rodriguez, Everardo, Rutt, Harvey N., Rojas-Laguna, Roberto, and Alavarado-Mendez, Edgar

Subjects
*FABRY-Perot interferometers, *MODULATION spectroscopy, *INTERFEROMETERS, *PYROELECTRIC detectors, *DETECTORS, *PHYSICS instruments, *SPECTRUM analysis
Abstract

A gas sensor design based on cross correlation spectroscopy using a FPI with long cavity length (>500 μm) as a modulator and with a pyroelectric detector is presented. This technique can be suitable to detect molecules with very well defined ro-vibrational lines such as CO, CO2 and CH4. To induce modulation one mirror of the FPI is scan over λ/2, this will shift the spectral FPI transmission fringe pattern producing the cross correlation principle. In this design the FPI is illuminated with a converging beam and it is placed just in front of the pyroelectric detector, this configuration can be useful if the FPI and the detector are integrated within a MEMS. Furthermore here the FPI scan is driven using a triangular waveform. Therefore in this work we will analyze the effects of illuminate the FPI with a converging beam and their consequences in the overall sensor response. Moreover we will review some possible effects in the sensor response for driving the FPI mirror scan with a triangular waveform. This issue can be very important since it can change the harmonic composition of the modulated signal and consequently the overall sensor response since the pyroelectric detector responsivity is frequency dependant. Finally, simulation results and experimental measurements are provided. [ABSTRACT FROM AUTHOR]

Published
2008
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