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Papers by mauro casalboni
In the present work we report on steady-state and dynamical optical properties of four polymethin... more In the present work we report on steady-state and dynamical optical properties of four polymethine dye molecules absorbing in the near infrared (IR) region (0.8-1.1 µm) and emitting around 1.2 µm. The molecules are embedded in organically modified silicate (ORMOSIL) material synthesized by a sol-gel method. The investigated samples were prepared as films, deposited on glass substrates. Steady-state absorption and emission measurements have been accomplished for the chromophores in solution as well as in hybrid organic/inorganic films in order to determine the effect of the solid cage on the optical properties of the chromophore. To better understand the influence of the solid network, we also measured for some of the investigated molecules emission transients with femtosecond time resolution. An estimation of the emission quantum yield of the IR dye molecules in a glassy matrix is also given. The kinetic results are sensitive to guest-host interactions.
Physical Review B, 1991
ABSTRACT
Physical Review B, 1991
Two-photon excitation of the Ag- centers in RbCl, RbBr, and KCl have been measured. From the depe... more Two-photon excitation of the Ag- centers in RbCl, RbBr, and KCl have been measured. From the dependence of luminescence on the polarization of the exciting beams, the symmetry of the final levels could be obtained. In all three host crystals, we observed an intense band assigned to the 1A1g-->1A1g transition. At higher energies 1A1g-->1Eg and 1A1g-->1T2g transitions could be identified but their presence and intensity change in the different crystals. On the high-energy side of the investigated range, we could observe an intense luminescence signal arising from a two-step excitation process; the exciting photon energy becoming resonant with the 3T1u state (A band).
Optics Communications, 1977
Radiation Effects, 1983
Two-photon excitation spectrum of the luminescence emitted in the AT-band has been observed in KB... more Two-photon excitation spectrum of the luminescence emitted in the AT-band has been observed in KBr:In and NaBr:Tl. The nonlinear excitation follows the A-band lineshape but reveals a feature, not present in one-photon spectrum, that may be interpreted as due to the forbidden AIg→AIu transition. The cross section of the process indicates that the two-photon transitions are indirect ones, allowed by
Physical Review B, 1995
ABSTRACT The optical properties of trivalent chromium ions in LaSr2Ga11O20 crystals have been inv... more ABSTRACT The optical properties of trivalent chromium ions in LaSr2Ga11O20 crystals have been investigated by means of absorption, emission, excitation, and lifetime measurements for various temperatures of the sample. The data so obtained allow us to determine the values of the crystal-field parameters in the framework of the Tanabe-Sugano model for the transition-metal ion in insulating crystals and glasses. In particular, the relatively narrow emission lines indicate a high value of the crystal field. Polarized absorption and excitation measurements have allowed the assignment of the electric dipole character to the two lowest-energy transitions. From polarized excitation measurements it was possible to infer the Cr3+-ion site distortion visible in a splitting of the otherwise degenerate 4T1 level. Moreover, the effect of tempeature on the emission bands’ intensities and lifetimes reveals the simultaneous presence of different competitive phenomena during the deexcitation of Cr3+ ion.
Radiation Effects and Defects in Solids, 1995
ABSTRACT The optical properties of Cr3+ ions in the disordered LaSr2Ga11O20 crystal have been inv... more ABSTRACT The optical properties of Cr3+ ions in the disordered LaSr2Ga11O20 crystal have been investigated through absorption, emission, excitation spectra. Polarized excitation measurements allows us to evaluate the crystal field parameters and to infer the distortion of the octahedral site of Cr3+. In spite of the relatively low value of the crystal field (Dq/B = 2.26) obtained from optical data, the emission spectra are constituted by two narrow lines. This behavior, typical of strong field material, is explained by an even lower value of the crystal field corresponding to the 2E, 4T2 crossing point obtained by means of the Tanabe-Sugano diagram. The value of the splitting and the width of the emission lines, intermediate between crystals and glasses, confirm the disordered structure of this crystal.
Radiation Effects and Defects in Solids, 1995
The optical properties of Ni-ion impurities in a new crystal, the inverted fluoroperovskite BaLiF... more The optical properties of Ni-ion impurities in a new crystal, the inverted fluoroperovskite BaLiF3, have been studied. In particular we have investigated the fine structure of the transition by means of absorption and emission spectra. By analogy to previous results we have assigned the structured absorption band around 1200 nm to the A2 → T1 transition. Four zero-phonon lines are
physica status solidi (c), 2010
physica status solidi (b), 1992
Optical Properties of (F2+)H Centers in NaCl : SH-Crystals BY M. CASALBONI (a), D. DE VIRY 3 , (a... more Optical Properties of (F2+)H Centers in NaCl : SH-Crystals BY M. CASALBONI (a), D. DE VIRY 3 , (a), U. M. GRASSANO (a), A. LUCI (a), M. PALUMMO (a), and A. SCACCO (b) The optical properties of the (Fl)H center are investigated in NaC1:SH-. The negative sulfur ion stabilizes the center in the same way as the oxygen ion does in the better known system NaCl: OH-. The spectral properties, absorption, emission, and excitation spectra, in the two cases are quite similar, but in NaCl: SH-the F : centers are more easily bound to the sulfur ion and this fact yields a greater stability to these centers. Die optischen Eigenschaften des (F;),-Zentrums in NaCl : SH-werden untersucht. Das negative Schwefelion stabilisiert das Zentrum in der gleichen Weise wie das Sauerstoffion es in dem besser bekannten System NaCl : OH tut. Die spektralen Eigenschaften, Absorptions-, Emissions-und Anregungsspektren, sind in beiden Fallen ganz ahnlich, jedoch sind die F:-Zentren in NaCl : SHschwacher an die Schwefelionen gebunden, was diesen Zentren eine groRere Stabilitat verleiht.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1985
Two-photon excited luminescence is proposed as a new method for homogeneity analysis of large BGO... more Two-photon excited luminescence is proposed as a new method for homogeneity analysis of large BGO crystals. This method allows to reach inner portions of the sample with good spatial resolution.
Materials Science and Engineering: C, 2007
We report on a photosensitive hybrid material based on 3-glycidoxypropyltrimethoxysilane (GPTMS) ... more We report on a photosensitive hybrid material based on 3-glycidoxypropyltrimethoxysilane (GPTMS) and on the cationic photopolymerization of the epoxide groups. In particular, we describe the synthesis and fabrication of patterned waveguide structures by ultraviolet (UV) irradiation through a quartz slide with a metallic mask. An increase of 0.01 of the material refractive index has been measured when the film is
Journal of Luminescence, 2001
We report on the optical properties of two dye molecules absorbing in the near infrared region (0... more We report on the optical properties of two dye molecules absorbing in the near infrared region (0.8-1.1 mm) and emitting up to 1.3 mm. The chromophores are embedded in hybrid organic/inorganic silicon-based films synthesized by a modified sol-gel technique. Femtosecond time-resolved emission spectra have been measured in order to determine the effect of the solid cage on the excited state dynamics of the trapped molecules. For comparison, measurements in different solvents are reported and an estimation of the relative quantum efficiency in solid glassy material with respect to liquid solutions is given. Measurements are discussed in terms of physical and chemical interactions with the host matrix.
Journal of Luminescence, 1984
In the present work we report on steady-state and dynamical optical properties of four polymethin... more In the present work we report on steady-state and dynamical optical properties of four polymethine dye molecules absorbing in the near infrared (IR) region (0.8-1.1 µm) and emitting around 1.2 µm. The molecules are embedded in organically modified silicate (ORMOSIL) material synthesized by a sol-gel method. The investigated samples were prepared as films, deposited on glass substrates. Steady-state absorption and emission measurements have been accomplished for the chromophores in solution as well as in hybrid organic/inorganic films in order to determine the effect of the solid cage on the optical properties of the chromophore. To better understand the influence of the solid network, we also measured for some of the investigated molecules emission transients with femtosecond time resolution. An estimation of the emission quantum yield of the IR dye molecules in a glassy matrix is also given. The kinetic results are sensitive to guest-host interactions.
Physical Review B, 1991
ABSTRACT
Physical Review B, 1991
Two-photon excitation of the Ag- centers in RbCl, RbBr, and KCl have been measured. From the depe... more Two-photon excitation of the Ag- centers in RbCl, RbBr, and KCl have been measured. From the dependence of luminescence on the polarization of the exciting beams, the symmetry of the final levels could be obtained. In all three host crystals, we observed an intense band assigned to the 1A1g-->1A1g transition. At higher energies 1A1g-->1Eg and 1A1g-->1T2g transitions could be identified but their presence and intensity change in the different crystals. On the high-energy side of the investigated range, we could observe an intense luminescence signal arising from a two-step excitation process; the exciting photon energy becoming resonant with the 3T1u state (A band).
Optics Communications, 1977
Radiation Effects, 1983
Two-photon excitation spectrum of the luminescence emitted in the AT-band has been observed in KB... more Two-photon excitation spectrum of the luminescence emitted in the AT-band has been observed in KBr:In and NaBr:Tl. The nonlinear excitation follows the A-band lineshape but reveals a feature, not present in one-photon spectrum, that may be interpreted as due to the forbidden AIg→AIu transition. The cross section of the process indicates that the two-photon transitions are indirect ones, allowed by
Physical Review B, 1995
ABSTRACT The optical properties of trivalent chromium ions in LaSr2Ga11O20 crystals have been inv... more ABSTRACT The optical properties of trivalent chromium ions in LaSr2Ga11O20 crystals have been investigated by means of absorption, emission, excitation, and lifetime measurements for various temperatures of the sample. The data so obtained allow us to determine the values of the crystal-field parameters in the framework of the Tanabe-Sugano model for the transition-metal ion in insulating crystals and glasses. In particular, the relatively narrow emission lines indicate a high value of the crystal field. Polarized absorption and excitation measurements have allowed the assignment of the electric dipole character to the two lowest-energy transitions. From polarized excitation measurements it was possible to infer the Cr3+-ion site distortion visible in a splitting of the otherwise degenerate 4T1 level. Moreover, the effect of tempeature on the emission bands’ intensities and lifetimes reveals the simultaneous presence of different competitive phenomena during the deexcitation of Cr3+ ion.
Radiation Effects and Defects in Solids, 1995
ABSTRACT The optical properties of Cr3+ ions in the disordered LaSr2Ga11O20 crystal have been inv... more ABSTRACT The optical properties of Cr3+ ions in the disordered LaSr2Ga11O20 crystal have been investigated through absorption, emission, excitation spectra. Polarized excitation measurements allows us to evaluate the crystal field parameters and to infer the distortion of the octahedral site of Cr3+. In spite of the relatively low value of the crystal field (Dq/B = 2.26) obtained from optical data, the emission spectra are constituted by two narrow lines. This behavior, typical of strong field material, is explained by an even lower value of the crystal field corresponding to the 2E, 4T2 crossing point obtained by means of the Tanabe-Sugano diagram. The value of the splitting and the width of the emission lines, intermediate between crystals and glasses, confirm the disordered structure of this crystal.
Radiation Effects and Defects in Solids, 1995
The optical properties of Ni-ion impurities in a new crystal, the inverted fluoroperovskite BaLiF... more The optical properties of Ni-ion impurities in a new crystal, the inverted fluoroperovskite BaLiF3, have been studied. In particular we have investigated the fine structure of the transition by means of absorption and emission spectra. By analogy to previous results we have assigned the structured absorption band around 1200 nm to the A2 → T1 transition. Four zero-phonon lines are
physica status solidi (c), 2010
physica status solidi (b), 1992
Optical Properties of (F2+)H Centers in NaCl : SH-Crystals BY M. CASALBONI (a), D. DE VIRY 3 , (a... more Optical Properties of (F2+)H Centers in NaCl : SH-Crystals BY M. CASALBONI (a), D. DE VIRY 3 , (a), U. M. GRASSANO (a), A. LUCI (a), M. PALUMMO (a), and A. SCACCO (b) The optical properties of the (Fl)H center are investigated in NaC1:SH-. The negative sulfur ion stabilizes the center in the same way as the oxygen ion does in the better known system NaCl: OH-. The spectral properties, absorption, emission, and excitation spectra, in the two cases are quite similar, but in NaCl: SH-the F : centers are more easily bound to the sulfur ion and this fact yields a greater stability to these centers. Die optischen Eigenschaften des (F;),-Zentrums in NaCl : SH-werden untersucht. Das negative Schwefelion stabilisiert das Zentrum in der gleichen Weise wie das Sauerstoffion es in dem besser bekannten System NaCl : OH tut. Die spektralen Eigenschaften, Absorptions-, Emissions-und Anregungsspektren, sind in beiden Fallen ganz ahnlich, jedoch sind die F:-Zentren in NaCl : SHschwacher an die Schwefelionen gebunden, was diesen Zentren eine groRere Stabilitat verleiht.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1985
Two-photon excited luminescence is proposed as a new method for homogeneity analysis of large BGO... more Two-photon excited luminescence is proposed as a new method for homogeneity analysis of large BGO crystals. This method allows to reach inner portions of the sample with good spatial resolution.
Materials Science and Engineering: C, 2007
We report on a photosensitive hybrid material based on 3-glycidoxypropyltrimethoxysilane (GPTMS) ... more We report on a photosensitive hybrid material based on 3-glycidoxypropyltrimethoxysilane (GPTMS) and on the cationic photopolymerization of the epoxide groups. In particular, we describe the synthesis and fabrication of patterned waveguide structures by ultraviolet (UV) irradiation through a quartz slide with a metallic mask. An increase of 0.01 of the material refractive index has been measured when the film is
Journal of Luminescence, 2001
We report on the optical properties of two dye molecules absorbing in the near infrared region (0... more We report on the optical properties of two dye molecules absorbing in the near infrared region (0.8-1.1 mm) and emitting up to 1.3 mm. The chromophores are embedded in hybrid organic/inorganic silicon-based films synthesized by a modified sol-gel technique. Femtosecond time-resolved emission spectra have been measured in order to determine the effect of the solid cage on the excited state dynamics of the trapped molecules. For comparison, measurements in different solvents are reported and an estimation of the relative quantum efficiency in solid glassy material with respect to liquid solutions is given. Measurements are discussed in terms of physical and chemical interactions with the host matrix.
Journal of Luminescence, 1984
