Time-resolved fluorescence studied at dielectric interfaces

Physical Aspects of Radiation-Induced Processes on SiO2, γ-Al2O3, Zeolites, and Clays

“…As given in Table , heating γ-Al 2 O 3 increases the extent of surface CT sites. This effect is readily seen by studies of the photophysics of adsorbed arenes on γ-Al 2 O 3 . − As in the SiO 2 system, a probe molecule of established photophysics is adsorbed onto γ-Al 2 O 3 , and the resulting spectroscopy is used to interpret the surface.…”

Physical aspects of photochemistry and radiation chemistry of molecules adsorbed on silica, .gamma.-alumina, zeolites, and clays

“…Electron donor-acceptor complexes (EDA) of several arenes, naphthalene, phenanthrene, and biphenyl are formed with the Lewis acid sites. [169][170][171][172][173][174] The EDA complexes are characterized by new unstructured fluorescence bands located at wavelengths shifted to the red of the spectra of the physically adsorbed species.…”

Second harmonic generation studies of methylene blue orientation at silica surfaces

“…(2 ) =----|ß(2 ). <2>:ß( ) eH2/2^) (2) <rA where /(«) is the intensity of input laser light, is the angle from the surface normal at which the SHG signal occurs, the vectors ß( ) and e(2<v) describe the polarization and Fresnel factors for the fundamental and second harmonic light fields at the surface. A is the illuminated surface area, and all other symbols have their usual meaning.…”

“…For methylene blue, at the wavelengths employed, two different molecular tensor elements are expected to contribute to the SHG response. The individual responses of the adsorbed molecules are then combined to form a surface nonlinear optical response that is characterized by the surface nonlinear susceptibility tensor (2).…”

“…The technique of fluorescence probing has been used to investigate the diffusion of adsorbed fluorescing polyaromatic hydrocarbons on silica and alumina. [1][2][3][4] The diffuse reflectance laser photolysis technique5 enables one to monitor triplet-triplet absorption of adsorbed hydrocarbons on these oxides.6 7"8 The literature indicates some disagreement regarding the effect of oxide pretreatment temperature on the diffusion processes on silica surfaces. A triplet-triplet annihilation study of acridine adsorbed on silica indicated that higher pretreatment temperatures cause the acridine to diffuse more slowly as the number of silanol groups is reduced.…”