We discuss recent DIET measurements of electronically desorbed neutrals. In each case the desorbe... more We discuss recent DIET measurements of electronically desorbed neutrals. In each case the desorbed neutral atoms are detected and velocity distributions determined from the analysis either of optical emission from the decay of emitted excited state atoms or of laser induced fluorescence (LIF) from ground state neutrals. The cases treated include: measurements of energy dependent yields and spectral lineshapes of Balmer radiation from excited hydrogen atoms desorbed from surfaces by electron impact, and LIF studies of velocity distributions of neutral ground state sodium atoms emitted from a sodium chloride surface due to electron stimulated desorption (ESD).
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1995
Defects induced by 20 keV ion bombardment of NaF and LiF crystals have been investigated by optic... more Defects induced by 20 keV ion bombardment of NaF and LiF crystals have been investigated by optical absorption and photo luminescence measurements. The F center band and F center aggregate bands have been identified in NaF and LiF crystals under argon ion bombardment. We found that the concentration of F centers is proportional to the square root of the ion dose on both samples. A recombination model of interstitial-vacancies is developed to explain this dependence.
ABSTRACT Second harmonic generation (SHG) laser spectroscopy has been demonstrated to be a powerf... more ABSTRACT Second harmonic generation (SHG) laser spectroscopy has been demonstrated to be a powerful, sensitive, and non-destructive analytical technique to study crystalline phases, domain structures, and molecular dipole orientations of ferroelectric polymeric thin films such as PVDF. While other spectroscopic techniques, such as WXRD and FTIR, do provide valuable information on the crystalline phases, they are not sensitive enough to provide the detailed information at molecular levels and properties at interfaces. The current study of single layered PVDF polymer has also shown that SHG can be further developed into an in-situ, sensitive and quantitative tool to study ferroelectric polymeric thin film structures. In combination, SHG and electric field induced SHG (EFISH) techniques will allow us to interrogate multilayered structures layer-by-layer, the effects of physical confinement and interfacial physics.
ABSTRACT In this work, the magnetic properties of the Fe/NiO (1 0 0) interface at room temperatur... more ABSTRACT In this work, the magnetic properties of the Fe/NiO (1 0 0) interface at room temperature is investigated using non-linear magneto-optical Kerr effect. Nickel oxide is a promising material for technological applications due to its Néel temperature (525 K) occurring well above the room temperature. Non-linear Kerr rotation measurements have demonstrated to be an effective way to investigate a ferro-magnetic/antiferromagnetic interface. The measurements here reported demonstrate that the magnetic properties of the studied interface strongly depend on the Fe layer thickness. In fact, a clear hysteresis loop is observed only for a thickness higher than 5 ML, whereas for the 2 ML sample the hysteresis loop completely disappears. These results are in agreement with previous structural characterizations of the interface.
... Circulation Director: Michael Spinella Deputy Director: Mariene Zendell Member Services: Rebe... more ... Circulation Director: Michael Spinella Deputy Director: Mariene Zendell Member Services: Rebecca Dickerson, Manager; Mary Curry, Supervisor, Pat Butler, Helen Williams, Laurie Baker, Representatives Marketing: Dee Valencia, Manager; Jane Pennington, Europe Manager ...
Abstract Desorption of alkali atoms from, and defects formed in, alkali halide crystals stimulate... more Abstract Desorption of alkali atoms from, and defects formed in, alkali halide crystals stimulated by low-energy electron bombardment were investigated simultaneously by optical absorption-, mass spectroscopy-, and depth-profile surface sputtering-techniques. ...
These proceedings of physica status solidi (c) contain papers presented at the 7th conference on ... more These proceedings of physica status solidi (c) contain papers presented at the 7th conference on Optics of Surfaces and Interfaces: From Basic Research to Applications (OSI‐VII) held in Grand Targhee, Wyoming, USA, 15–20 July 2007. The OSI‐VII meeting is a continuation of a now established tradition of Epioptics workshops, Surface and Interface Optics conferences, and summer schools at Erice, Italy held since 1992. Starting with OSI‐V in León, Mexico in 2003 the new series of OSI conferences is organized every second year alternating with the Erice summer school devoted to the same topic.OSI‐VII brought together 55 researchers and students from universities and institutes around the world working in different fields of optical spectroscopy at surfaces and interfaces. The goal was to evaluate the status of surface optical spectroscopy, seeking a closer connection between theory and experiment, and their interconnection with applied research. During the conference 65 presentations wer...
We review recent second harmonic generation (SHG) measurements for highly boron‐doped Si/SiO2 sys... more We review recent second harmonic generation (SHG) measurements for highly boron‐doped Si/SiO2 systems. Using electric field sensitive time‐dependent SHG (TD‐SHG), we determined that the direction of the initial DC electric field at the interface induced by boron induced charge traps is from oxide to silicon thus demonstrating that the boron induced charge traps in the oxide are positively charged. For a thin oxide (∼2 nm) both boron traps and O2 surface oxide traps contribute. However, for a highly boron‐doped Si/SiO2 sample with a thick thermally grown oxide (thickness: 12 nm), the TD‐SHG signal exhibits a monotonic decrease arising from filling only the boron charge traps. By fitting our data, we show that the interface effective susceptibility |χ(2)| is heavily dependent on doping concentration.
Physica E: Low-dimensional Systems and Nanostructures, 2005
We have initiated experiments on interface fluctuation quantum dots in the GaAs/AlGaAs system wit... more We have initiated experiments on interface fluctuation quantum dots in the GaAs/AlGaAs system with the goal of elucidating the excited states of excitons and the coupling of the center-of-mass and relative motion in the weak lateral confining potential. Magneto-PL and optically detected resonance (ODR) spectroscopy are carried out with a grating spectrometer/ccd system and an optical-access superconducting magnet (10 T).
Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tenness... more Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.
We discuss recent DIET measurements of electronically desorbed neutrals. In each case the desorbe... more We discuss recent DIET measurements of electronically desorbed neutrals. In each case the desorbed neutral atoms are detected and velocity distributions determined from the analysis either of optical emission from the decay of emitted excited state atoms or of laser induced fluorescence (LIF) from ground state neutrals. The cases treated include: measurements of energy dependent yields and spectral lineshapes of Balmer radiation from excited hydrogen atoms desorbed from surfaces by electron impact, and LIF studies of velocity distributions of neutral ground state sodium atoms emitted from a sodium chloride surface due to electron stimulated desorption (ESD).
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1995
Defects induced by 20 keV ion bombardment of NaF and LiF crystals have been investigated by optic... more Defects induced by 20 keV ion bombardment of NaF and LiF crystals have been investigated by optical absorption and photo luminescence measurements. The F center band and F center aggregate bands have been identified in NaF and LiF crystals under argon ion bombardment. We found that the concentration of F centers is proportional to the square root of the ion dose on both samples. A recombination model of interstitial-vacancies is developed to explain this dependence.
ABSTRACT Second harmonic generation (SHG) laser spectroscopy has been demonstrated to be a powerf... more ABSTRACT Second harmonic generation (SHG) laser spectroscopy has been demonstrated to be a powerful, sensitive, and non-destructive analytical technique to study crystalline phases, domain structures, and molecular dipole orientations of ferroelectric polymeric thin films such as PVDF. While other spectroscopic techniques, such as WXRD and FTIR, do provide valuable information on the crystalline phases, they are not sensitive enough to provide the detailed information at molecular levels and properties at interfaces. The current study of single layered PVDF polymer has also shown that SHG can be further developed into an in-situ, sensitive and quantitative tool to study ferroelectric polymeric thin film structures. In combination, SHG and electric field induced SHG (EFISH) techniques will allow us to interrogate multilayered structures layer-by-layer, the effects of physical confinement and interfacial physics.
ABSTRACT In this work, the magnetic properties of the Fe/NiO (1 0 0) interface at room temperatur... more ABSTRACT In this work, the magnetic properties of the Fe/NiO (1 0 0) interface at room temperature is investigated using non-linear magneto-optical Kerr effect. Nickel oxide is a promising material for technological applications due to its Néel temperature (525 K) occurring well above the room temperature. Non-linear Kerr rotation measurements have demonstrated to be an effective way to investigate a ferro-magnetic/antiferromagnetic interface. The measurements here reported demonstrate that the magnetic properties of the studied interface strongly depend on the Fe layer thickness. In fact, a clear hysteresis loop is observed only for a thickness higher than 5 ML, whereas for the 2 ML sample the hysteresis loop completely disappears. These results are in agreement with previous structural characterizations of the interface.
... Circulation Director: Michael Spinella Deputy Director: Mariene Zendell Member Services: Rebe... more ... Circulation Director: Michael Spinella Deputy Director: Mariene Zendell Member Services: Rebecca Dickerson, Manager; Mary Curry, Supervisor, Pat Butler, Helen Williams, Laurie Baker, Representatives Marketing: Dee Valencia, Manager; Jane Pennington, Europe Manager ...
Abstract Desorption of alkali atoms from, and defects formed in, alkali halide crystals stimulate... more Abstract Desorption of alkali atoms from, and defects formed in, alkali halide crystals stimulated by low-energy electron bombardment were investigated simultaneously by optical absorption-, mass spectroscopy-, and depth-profile surface sputtering-techniques. ...
These proceedings of physica status solidi (c) contain papers presented at the 7th conference on ... more These proceedings of physica status solidi (c) contain papers presented at the 7th conference on Optics of Surfaces and Interfaces: From Basic Research to Applications (OSI‐VII) held in Grand Targhee, Wyoming, USA, 15–20 July 2007. The OSI‐VII meeting is a continuation of a now established tradition of Epioptics workshops, Surface and Interface Optics conferences, and summer schools at Erice, Italy held since 1992. Starting with OSI‐V in León, Mexico in 2003 the new series of OSI conferences is organized every second year alternating with the Erice summer school devoted to the same topic.OSI‐VII brought together 55 researchers and students from universities and institutes around the world working in different fields of optical spectroscopy at surfaces and interfaces. The goal was to evaluate the status of surface optical spectroscopy, seeking a closer connection between theory and experiment, and their interconnection with applied research. During the conference 65 presentations wer...
We review recent second harmonic generation (SHG) measurements for highly boron‐doped Si/SiO2 sys... more We review recent second harmonic generation (SHG) measurements for highly boron‐doped Si/SiO2 systems. Using electric field sensitive time‐dependent SHG (TD‐SHG), we determined that the direction of the initial DC electric field at the interface induced by boron induced charge traps is from oxide to silicon thus demonstrating that the boron induced charge traps in the oxide are positively charged. For a thin oxide (∼2 nm) both boron traps and O2 surface oxide traps contribute. However, for a highly boron‐doped Si/SiO2 sample with a thick thermally grown oxide (thickness: 12 nm), the TD‐SHG signal exhibits a monotonic decrease arising from filling only the boron charge traps. By fitting our data, we show that the interface effective susceptibility |χ(2)| is heavily dependent on doping concentration.
Physica E: Low-dimensional Systems and Nanostructures, 2005
We have initiated experiments on interface fluctuation quantum dots in the GaAs/AlGaAs system wit... more We have initiated experiments on interface fluctuation quantum dots in the GaAs/AlGaAs system with the goal of elucidating the excited states of excitons and the coupling of the center-of-mass and relative motion in the weak lateral confining potential. Magneto-PL and optically detected resonance (ODR) spectroscopy are carried out with a grating spectrometer/ccd system and an optical-access superconducting magnet (10 T).
Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tenness... more Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.
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