Avoiding photothermal noise in laser assisted scanning tunneling microscopy

Thermal expansion produced by laser irradiation of the tunneling junction is analyzed, as a necessary step towards detection and identification of other laser induced currents in scanning tunneling microscopy (STM). Solving a tridimensional heat diffusion model, the amplitude of thermal expansion as...

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Autores principales:	Landi, Sandra Marcela, Bragas, Andrea Verónica, Martínez, Oscar Eduardo
Publicado:	1999
Materias:	Laser assisted Photothermal currents Scanning tunneling microscope Thermal noise Computational methods Electric currents Gold Graphite Laser beam effects Mathematical models Signal to noise ratio Thermal diffusion Thermal expansion Gaussian beams Photothermal noise Scanning tunneling microscopy analytic method article frequency modulation heat transfer laser mathematical analysis scanning tunneling microscopy signal noise ratio thermal exposure
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03043991_v77_n3-4_p207_Landi http://hdl.handle.net/20.500.12110/paper_03043991_v77_n3-4_p207_Landi
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_03043991_v77_n3-4_p207_Landi
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spelling	paper:paper_03043991_v77_n3-4_p207_Landi2023-06-08T15:29:41Z Avoiding photothermal noise in laser assisted scanning tunneling microscopy Landi, Sandra Marcela Bragas, Andrea Verónica Martínez, Oscar Eduardo Laser assisted Photothermal currents Scanning tunneling microscope Thermal noise Computational methods Electric currents Gold Graphite Laser beam effects Mathematical models Signal to noise ratio Thermal diffusion Thermal expansion Gaussian beams Photothermal noise Scanning tunneling microscopy analytic method article frequency modulation heat transfer laser mathematical analysis scanning tunneling microscopy signal noise ratio thermal exposure Thermal expansion produced by laser irradiation of the tunneling junction is analyzed, as a necessary step towards detection and identification of other laser induced currents in scanning tunneling microscopy (STM). Solving a tridimensional heat diffusion model, the amplitude of thermal expansion as a function of the modulation frequency (ω) of the light power, rolls off as 1/ω while the in-phase component rolls off as 1/ω2, both computed at the Gaussian beam center. But shifted from the center a dephasing mechanism appears due to the lateral diffusion of the heat, and the in-phase thermal contribution drops to zero. This behavior can be used to increase the signal to noise ratio without the need of driving the experiment at high frequencies, frequently over the usual cutoff frequency of STM amplifiers. Experiments were carried on using a low power laser on highly oriented pyrolitic graphite (HOPG) and gold samples, showing a qualitative agreement with the model. Thermal expansion produced by laser irradiation of the tunneling junction is analyzed, as a necessary step towards detection and identification of other laser induced currents in scanning tunneling microscopy (STM). Solving a tridimensional heat diffusion model, the amplitude of thermal expansion as a function of the modulation frequency (ω) of the light power, rolls off as 1/ω while the in-phase component rolls off as 1/ω+2$/, both computed at the Gaussian beam center. But shifted from the center a dephasing mechanism appears due to the lateral diffusion of the heat, and the in-phase thermal contribution drops to zero. This behavior can be used to increase the signal to noise ratio without the need of driving the experiment at high frequencies, frequently over the usual cutoff frequency of STM amplifiers. Experiments were carried on using a low power laser on highly oriented pyrolitic graphite (HOPG) and gold samples, showing a qualitative agreement with the model. Fil:Landi, S.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Bragas, A.V. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Martínez, O.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1999 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03043991_v77_n3-4_p207_Landi http://hdl.handle.net/20.500.12110/paper_03043991_v77_n3-4_p207_Landi
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Laser assisted Photothermal currents Scanning tunneling microscope Thermal noise Computational methods Electric currents Gold Graphite Laser beam effects Mathematical models Signal to noise ratio Thermal diffusion Thermal expansion Gaussian beams Photothermal noise Scanning tunneling microscopy analytic method article frequency modulation heat transfer laser mathematical analysis scanning tunneling microscopy signal noise ratio thermal exposure
spellingShingle	Laser assisted Photothermal currents Scanning tunneling microscope Thermal noise Computational methods Electric currents Gold Graphite Laser beam effects Mathematical models Signal to noise ratio Thermal diffusion Thermal expansion Gaussian beams Photothermal noise Scanning tunneling microscopy analytic method article frequency modulation heat transfer laser mathematical analysis scanning tunneling microscopy signal noise ratio thermal exposure Landi, Sandra Marcela Bragas, Andrea Verónica Martínez, Oscar Eduardo Avoiding photothermal noise in laser assisted scanning tunneling microscopy
topic_facet	Laser assisted Photothermal currents Scanning tunneling microscope Thermal noise Computational methods Electric currents Gold Graphite Laser beam effects Mathematical models Signal to noise ratio Thermal diffusion Thermal expansion Gaussian beams Photothermal noise Scanning tunneling microscopy analytic method article frequency modulation heat transfer laser mathematical analysis scanning tunneling microscopy signal noise ratio thermal exposure
description	Thermal expansion produced by laser irradiation of the tunneling junction is analyzed, as a necessary step towards detection and identification of other laser induced currents in scanning tunneling microscopy (STM). Solving a tridimensional heat diffusion model, the amplitude of thermal expansion as a function of the modulation frequency (ω) of the light power, rolls off as 1/ω while the in-phase component rolls off as 1/ω2, both computed at the Gaussian beam center. But shifted from the center a dephasing mechanism appears due to the lateral diffusion of the heat, and the in-phase thermal contribution drops to zero. This behavior can be used to increase the signal to noise ratio without the need of driving the experiment at high frequencies, frequently over the usual cutoff frequency of STM amplifiers. Experiments were carried on using a low power laser on highly oriented pyrolitic graphite (HOPG) and gold samples, showing a qualitative agreement with the model. Thermal expansion produced by laser irradiation of the tunneling junction is analyzed, as a necessary step towards detection and identification of other laser induced currents in scanning tunneling microscopy (STM). Solving a tridimensional heat diffusion model, the amplitude of thermal expansion as a function of the modulation frequency (ω) of the light power, rolls off as 1/ω while the in-phase component rolls off as 1/ω+2$/, both computed at the Gaussian beam center. But shifted from the center a dephasing mechanism appears due to the lateral diffusion of the heat, and the in-phase thermal contribution drops to zero. This behavior can be used to increase the signal to noise ratio without the need of driving the experiment at high frequencies, frequently over the usual cutoff frequency of STM amplifiers. Experiments were carried on using a low power laser on highly oriented pyrolitic graphite (HOPG) and gold samples, showing a qualitative agreement with the model.
author	Landi, Sandra Marcela Bragas, Andrea Verónica Martínez, Oscar Eduardo
author_facet	Landi, Sandra Marcela Bragas, Andrea Verónica Martínez, Oscar Eduardo
author_sort	Landi, Sandra Marcela
title	Avoiding photothermal noise in laser assisted scanning tunneling microscopy
title_short	Avoiding photothermal noise in laser assisted scanning tunneling microscopy
title_full	Avoiding photothermal noise in laser assisted scanning tunneling microscopy
title_fullStr	Avoiding photothermal noise in laser assisted scanning tunneling microscopy
title_full_unstemmed	Avoiding photothermal noise in laser assisted scanning tunneling microscopy
title_sort	avoiding photothermal noise in laser assisted scanning tunneling microscopy
publishDate	1999
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03043991_v77_n3-4_p207_Landi http://hdl.handle.net/20.500.12110/paper_03043991_v77_n3-4_p207_Landi
work_keys_str_mv	AT landisandramarcela avoidingphotothermalnoiseinlaserassistedscanningtunnelingmicroscopy AT bragasandreaveronica avoidingphotothermalnoiseinlaserassistedscanningtunnelingmicroscopy AT martinezoscareduardo avoidingphotothermalnoiseinlaserassistedscanningtunnelingmicroscopy
_version_	1768544180568588288

Avoiding photothermal noise in laser assisted scanning tunneling microscopy

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