Generation mechanism of photoinduced paramagnetic centers from preexisting precursors in high-purity silicas

Hiroyuki Nishikawa; Ryuta Nakamura; Ryoichi Tohmon; Yoshimichi Ohki; Yuryo Sakurai; Kaya Nagasawa; Yoshimasa Hama

doi:10.1103/PhysRevB.41.7828

Generation mechanism of photoinduced paramagnetic centers from preexisting precursors in high-purity silicas

Hiroyuki Nishikawa^*, Ryuta Nakamura, Ryoichi Tohmon, Yoshimichi Ohki, Yuryo Sakurai, Kaya Nagasawa, Yoshimasa Hama

^*Corresponding author for this work

School of Advanced Science and Engineering

Research output: Contribution to journal › Article › peer-review

92 Citations (Scopus)

Abstract

High-purity silicas synthesized by various manufacturing methods were studied by electron-spin resonance after being irradiated by ArF excimer laser (6.4 eV) at room temperature. Ee centers (?Si) are induced in all samples, while nonbridging oxygen hole centers (?Si-O) appear only in oxygen-surplus silicas and in a sample which has an absorption band at 5.1 eV. The concentration of Ee centers varies from sample to sample, ranging between 1014 and 1016 spins/cm3 for the exposure at the average power density of 28 mJ/cm2 per pulse at 15 Hz for 1 h. The sample dependence regarding the species and concentrations of photoinduced defects is well explained in terms of transformation of preexisting precursors to paramagnetic defects through a two-photon-absorption process.

Original language	English
Pages (from-to)	7828-7834
Number of pages	7
Journal	Physical Review B
Volume	41
Issue number	11
DOIs	https://doi.org/10.1103/PhysRevB.41.7828
Publication status	Published - 1990 Jan 1

ASJC Scopus subject areas

Condensed Matter Physics

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10.1103/PhysRevB.41.7828

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abstract = "High-purity silicas synthesized by various manufacturing methods were studied by electron-spin resonance after being irradiated by ArF excimer laser (6.4 eV) at room temperature. Ee centers (?Si) are induced in all samples, while nonbridging oxygen hole centers (?Si-O) appear only in oxygen-surplus silicas and in a sample which has an absorption band at 5.1 eV. The concentration of Ee centers varies from sample to sample, ranging between 1014 and 1016 spins/cm3 for the exposure at the average power density of 28 mJ/cm2 per pulse at 15 Hz for 1 h. The sample dependence regarding the species and concentrations of photoinduced defects is well explained in terms of transformation of preexisting precursors to paramagnetic defects through a two-photon-absorption process.",

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T1 - Generation mechanism of photoinduced paramagnetic centers from preexisting precursors in high-purity silicas

AU - Nishikawa, Hiroyuki

AU - Nakamura, Ryuta

AU - Tohmon, Ryoichi

AU - Ohki, Yoshimichi

AU - Sakurai, Yuryo

AU - Nagasawa, Kaya

AU - Hama, Yoshimasa

PY - 1990/1/1

Y1 - 1990/1/1

N2 - High-purity silicas synthesized by various manufacturing methods were studied by electron-spin resonance after being irradiated by ArF excimer laser (6.4 eV) at room temperature. Ee centers (?Si) are induced in all samples, while nonbridging oxygen hole centers (?Si-O) appear only in oxygen-surplus silicas and in a sample which has an absorption band at 5.1 eV. The concentration of Ee centers varies from sample to sample, ranging between 1014 and 1016 spins/cm3 for the exposure at the average power density of 28 mJ/cm2 per pulse at 15 Hz for 1 h. The sample dependence regarding the species and concentrations of photoinduced defects is well explained in terms of transformation of preexisting precursors to paramagnetic defects through a two-photon-absorption process.

AB - High-purity silicas synthesized by various manufacturing methods were studied by electron-spin resonance after being irradiated by ArF excimer laser (6.4 eV) at room temperature. Ee centers (?Si) are induced in all samples, while nonbridging oxygen hole centers (?Si-O) appear only in oxygen-surplus silicas and in a sample which has an absorption band at 5.1 eV. The concentration of Ee centers varies from sample to sample, ranging between 1014 and 1016 spins/cm3 for the exposure at the average power density of 28 mJ/cm2 per pulse at 15 Hz for 1 h. The sample dependence regarding the species and concentrations of photoinduced defects is well explained in terms of transformation of preexisting precursors to paramagnetic defects through a two-photon-absorption process.

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Generation mechanism of photoinduced paramagnetic centers from preexisting precursors in high-purity silicas

Abstract

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