Photothermal spectroscopy

Brilmyer, G.H.; Fujishima, Akira; Santhanam, K. S. V.; Bard, Allen J.

doi:10.1021/ac50021a042

Cited by 57 publications

(14 citation statements)

References 17 publications

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“…We recently described a new spectroscopic method called Photothermal Spectroscopy (PTS) (16). This technique involves placing a thermistor on or in close proximity to a sample and measuring temperature changes (i.e., thermistor resistance changes) during sample irradiation with monochromatic light.…”

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confidence: 99%

Simultaneous Determination of Quantum Efficiency and Energy Efficiency of Semiconductor Photoelectrochemical Cells by Photothermal Spectroscopy

Fujishima

Maeda

Honda

et al. 1980

J. Electrochem. Soc.

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During a photoelectrochemical reaction only a portion of the light energy absorbed by the semiconductor (CdS or TiO2 single crystal) is utilized in the electrode reaction. The unused portion of energy is expended through various mechanisms as heat. Therefore by monitoring temperature changes within the photoanode as a function of electrode potential and light intensity, information concerning the efficiency of the process can be obtained. Experimental results are presented and interpreted using a model for the energy balance within the system. This permits the determination of the quantum and energy efficiencies simultaneously without the need to calibrate the light source.A number of photoelectrochemical cells based on semiconductor electrodes for photoelectrosynthesis (e.g,, the photodecomposition of water) and the conversion of solar energy to electricity have ,been reported (!-15). The major factors determining the efficacy of these semiconductor electrode ceils are the quantum efficiency for electron flow (i.e., number of electrons flowing/number of photons absorbed), and the power conversion efficiency (i.e., chemical or electrical power output/input radiant power). It is not uncommon to find near unity quantum yields for electron flow at a sufficiently high bias (positive for the case of n-type semiconductors) during irradiation with greater than bandgap energy light for many semiconductors. However, even when high quantum efficiencies have been obtained, the power efficiencies were much lower (10-15). For example, for photooxidation at a CdS single crystal anode, Wrighton et al. (15) reported that with an Se 2-solution the maximum monochromatic power efficiency obtained was 3.4% with a maximum quantum efficiency of 49%. Such findings demonstrate that the major part of the light energy absorbed by the semiconductor is not used for the photo-assisted oxidation but rather is converted to heat energy probably via radiationless transitions within the conduction band of the semiconductor (i.e., when the photon energy is in excess of the bandgap energy) or electron-hole recombination processes. Consequently, thermal measurements of the semiconductor electrode during etectroIysis can aid in the determination of the efficiencies and perhaps in the elucidation of the mechanism of the cell processes.We recently described a new spectroscopic method called Photothermal Spectroscopy (PTS) (16). This technique involves placing a thermistor on or in close proximity to a sample and measuring temperature changes (i.e., thermistor resistance changes) during sample irradiation with monochromatic light. This technique can be easily adapted to cases when the sample is a semiconductor electrode (17). Cahen (18) has also shown that similar measurements with photoacoustic spectroscopy can be used to determine the efficiency of solid-state photovoltaic devices. We report in this paper measurements of the conversion of light energy to chemical and/or electrical energy at * Electrochemical Society Active Member. ~ Electrochemical So...

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confidence: 99%

Simultaneous Determination of Quantum Efficiency and Energy Efficiency of Semiconductor Photoelectrochemical Cells by Photothermal Spectroscopy

Fujishima

Maeda

Honda

et al. 1980

J. Electrochem. Soc.

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“…Analytic solutions exist in the literature for the temperature profile of many geometries (see References 9,10,12,14,23,66,and The basic PDS system is shown in Figure 3-1. We can consider the system in terms of three subsystems: excitation, detection, and electronics.…”

Section: Resultsmentioning

confidence: 99%

“…• OH [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] where s 0 H is the stoichiometric coefficient ofPt(OH)2 (which is 1 in this case).…”

Section: I(t)mentioning

confidence: 99%

Application of photothermal deflection spectroscopy to electrochemical interfaces

Rudnicki¹,

McLarnon²,

Cairns³

1992

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“…This was based, in part, on published reports of photothermal optical coherence tomography, 14 photoacoustic imaging, 15 pulsed photothermal radiometry, 16 and photothermal spectroscopy. 17 Here we describe experiments designed to identify the primary mechanism by which photothermal LSI decreases speckle contrast. We proposed the following three hypotheses:…”

Section: Introductionmentioning

confidence: 99%

Laser speckle imaging based on photothermally driven convection

Regan

Choi

2016

J. Biomed. Opt.

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Abstract. Laser speckle imaging (LSI) is an interferometric technique that provides information about the relative speed of moving scatterers in a sample. Photothermal LSI overcomes limitations in depth resolution faced by conventional LSI by incorporating an excitation pulse to target absorption by hemoglobin within the vascular network. Here we present results from experiments designed to determine the mechanism by which photothermal LSI decreases speckle contrast. We measured the impact of mechanical properties on speckle contrast, as well as the spatiotemporal temperature dynamics and bulk convective motion occurring during photothermal LSI. Our collective data strongly support the hypothesis that photothermal LSI achieves a transient reduction in speckle contrast due to bulk motion associated with thermally driven convection. The ability of photothermal LSI to image structures below a scattering medium may have important preclinical and clinical applications.

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Photothermal spectroscopy

Cited by 57 publications

References 17 publications

Simultaneous Determination of Quantum Efficiency and Energy Efficiency of Semiconductor Photoelectrochemical Cells by Photothermal Spectroscopy

Simultaneous Determination of Quantum Efficiency and Energy Efficiency of Semiconductor Photoelectrochemical Cells by Photothermal Spectroscopy

Application of photothermal deflection spectroscopy to electrochemical interfaces

Laser speckle imaging based on photothermally driven convection

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