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Photoexcitation
About: Photoexcitation is a research topic. Over the lifetime, 5874 publications have been published within this topic receiving 134733 citations.
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TL;DR: In this article, the growth and decay of the electron reduction peak are investigated experimentally and the peak is analyzed as a reduction by conduction band electrons of surface states that were oxidized by valence band holes during the photoexcitation.
Abstract: When a electrode in an aqueous electrolyte is biased enough positive of its flatband potential and then photoexcited with light of wavelength shorter than 400 nm, photocurrent is observed. If the electrode is subsequently swept to more negative voltages in the dark a negative current is observed which is in excess of the normal dark current observed on a subsequent sweep with no photoexcitation between sweeps. The excess current is observed to have a maximum at a voltage positive of the flatband potential. In this paper, the growth and decay of this reduction peak are investigated experimentally. The peak is analyzed as a reduction by conduction band electrons of surface states that were oxidized by valence band holes during the photoexcitation. The observations favor the interpretation that these states are intermediates of the reaction leading to evolution. This interpretation, however, is not unequivocally established. It is clear that the conduction‐band electron reduction of a state that was previously oxidized by a valence‐band hole is in effect an electron‐hole recombination. This recombination controls the onset of photocurrent with voltage. There are 1013–1014 of these states per cm2 and the cross section for electron interaction with this surface state is estimated to be 10−16–10−17 cm2 based on the analysis used to describe the peak. The usefulness of this analysis in investigating these states and surface states due to surface coatings is discussed.
85 citations
TL;DR: In this paper, the dielectric properties of quantum paraelectric SrTiO 3 under UV-light illumination from 100 Hz to 1 MHz at low temperatures were studied.
Abstract: Dielectric properties are studied in quantum paraelectric SrTiO 3 under UV-light illumination from 100 Hz to 1 MHz at low temperatures We demonstrate that the complex dielectric constant is strong
85 citations
TL;DR: In this article, the authors employed picosecond pump-probe techniques in conjunction with a tandem time-of-flight mass spectrometer to investigate the caging dynamics of photodissociated I2− solvated with a specific number of CO2 molecules.
Abstract: We have employed picosecond pump–probe techniques in conjunction with a tandem time‐of‐flight mass spectrometer to investigate the caging dynamics of photodissociated I2− solvated with a specific number of CO2 molecules. In this paper, we report the observation of a recurrence at ≊2 ps in the I2− absorption recovery, a feature which is attributed to coherent I...I− nuclear motion following I2− photoexcitation.
84 citations
TL;DR: The mechanism of charge transfer between energy states of electrons in electrodes and redox systems was studied in this paper, where it was shown that not only conduction and valence band but also surface states are involved in the charge transfer at the interface.
Abstract: The mechanism of the charge transfer between energy states of electrons in electrodes and redox systems was studied. Measurements of the photoexcitation of electrons in have shown that not only the conduction and valence band but also surface states are involved in the charge transfer at the interface. Electroluminescence is observed if minority carriers are injected into the electrode. The corresponding recombination process is compared with that of the photoluminescence. Quenching effects are discussed.
84 citations
TL;DR: In this article, the authors combine electron paramagnetic resonance under optical excitation, deep level transient spectroscopy, electron irradiation, annealing, and quenching on LEC semi-insulating GaAs and lightly Si-doped material grown in the same way as the semiinsulating material.
Abstract: Combining electron paramagnetic resonance under optical excitation, deep level transient spectroscopy, electron irradiation, annealing, and quenching on LEC semi‐insulating GaAs and lightly Si‐doped material grown in the same way as the semi‐insulating material, we have shown that (i) the irradiated material contains two types of defects related to the antisite AsGa, one As∇Ga, present before irradiation, identified to EL2 from its characteristic photoquenching behavior and the other As*Ga, created by the irradiation, stable under photoexcitation; (ii) As∇Ga anneals partially under a 850 °C thermal treatment followed by a quench and the remaining defects are transformed into As*Ga; (iii) further annealing around 120 °C converts As*Ga into As∇Ga, the process being thermally activated (0.5±0.2 eV). From these results and using observations of absorption on vibrational modes of the C‐As interstitial pair in electron irradiated material, we are able to conclude that As*Ga is the isolated antisite and As∇Ga, i...
84 citations