TY - JOUR

T1 - Spectral dependence of UV light penetration into powder TiO2 anatase

AU - Михайлов, Руслан Вячеславович

AU - Лаврик, Полина Евгеньевна

AU - Кузнецов, Вячеслав Никитич

AU - Глазкова, Надежда Ивановна

N1 - Publisher Copyright: © 2022 Elsevier B.V.

PY - 2022/9/1

Y1 - 2022/9/1

N2 - The penetration depth of UV monochromatic light into deposited TiO2 anatase powder was investigated. Thelight penetration depth was considered in units of numbers of surface hole, Ns, and electron, NO2, centersactivated during irradiation. The numbers of hole centers Ns were obtained from photostimulated oxygen isotopeexchange reaction registered by means of mass spectrometry. The numbers of electron centers NO2 were obtainedfrom subsequent thermo-programmed desorption spectroscopy of photoadsorbed oxygen O−2 . It was shown thatthe depth D of UV light penetration into UV absorbing TiO2 powder coat depends on the wavelength and intensity I0 of incident UV light and obeys to the equation D(I0) = 1keff lg(I0/Im) obtained from the Beer–Lambert–Bouguer law with effective extinction coefficient keff and minimal value of light intensity Im, belowwhich the photoactivation is considered negligible. Commonly, the value Im has an order of a few microwatts/cm2 for activation of electron and hole type centers except for a case of 334 nm falling into the band of the firstdirect band-to-band transition of anatase, where relatively high threshold value Im=0.063 mW/cm2 for photoactivation of hole centers was revealed. Effective extinction coefficient keff may be considered proportional to theabsorption coefficient of TiO2 in the region of fundamental absorption, whereas, in the non-fundamental absorption region, keff exceeds significantly that of TiO2 due to, probably, dominating scattering processes. At smallintensities of the incident light, there is a strong sensitivity of the penetration depth (and activated surface) to theintensity.

AB - The penetration depth of UV monochromatic light into deposited TiO2 anatase powder was investigated. Thelight penetration depth was considered in units of numbers of surface hole, Ns, and electron, NO2, centersactivated during irradiation. The numbers of hole centers Ns were obtained from photostimulated oxygen isotopeexchange reaction registered by means of mass spectrometry. The numbers of electron centers NO2 were obtainedfrom subsequent thermo-programmed desorption spectroscopy of photoadsorbed oxygen O−2 . It was shown thatthe depth D of UV light penetration into UV absorbing TiO2 powder coat depends on the wavelength and intensity I0 of incident UV light and obeys to the equation D(I0) = 1keff lg(I0/Im) obtained from the Beer–Lambert–Bouguer law with effective extinction coefficient keff and minimal value of light intensity Im, belowwhich the photoactivation is considered negligible. Commonly, the value Im has an order of a few microwatts/cm2 for activation of electron and hole type centers except for a case of 334 nm falling into the band of the firstdirect band-to-band transition of anatase, where relatively high threshold value Im=0.063 mW/cm2 for photoactivation of hole centers was revealed. Effective extinction coefficient keff may be considered proportional to theabsorption coefficient of TiO2 in the region of fundamental absorption, whereas, in the non-fundamental absorption region, keff exceeds significantly that of TiO2 due to, probably, dominating scattering processes. At smallintensities of the incident light, there is a strong sensitivity of the penetration depth (and activated surface) to theintensity.

KW - Hombifine N

KW - Light penetration depth

KW - Oxygen isotope exchange

KW - TPD of oxygen

KW - Titanium dioxide

UR - https://www.sciencedirect.com/science/article/pii/S1010603022001836?dgcid=coauthor

UR - http://www.scopus.com/inward/record.url?scp=85129451992&partnerID=8YFLogxK

U2 - 10.1016/j.jphotochem.2022.113954

DO - 10.1016/j.jphotochem.2022.113954

M3 - Article

VL - 430

JO - Journal of Photochemistry and Photobiology A: Chemistry

JF - Journal of Photochemistry and Photobiology A: Chemistry

SN - 1010-6030

M1 - 113954

ER -