Thermal effects on zero-phonon holes in the optical spectra of molecular probes in polymer glasses

2003 ◽  
Vol 68 (6) ◽  
Author(s):  
Indrek Renge
Keyword(s):  
Thermal Effects ◽  
Optical Spectra ◽  
Molecular Probes ◽  
Polymer Glasses

scholarly journals Environmentally Sensitive Luminescence Reveals Spatial Confinement, Dynamics and Their Molecular Weight Dependence in a Polymer Glass

2021 ◽  
Author(s):  
Stephen Picken ◽  
Georgy Filonenko
Keyword(s):  
Molecular Weight ◽  
Molecular Probes ◽  
Key Factors ◽  
Polymer Glasses ◽  
Polymer Glass ◽  
Irregular Structure ◽  
Glassy Materials ◽  
Environmentally Sensitive ◽  
Induced Defects ◽  
The Impact

Polymer glasses have an irregular structure. Among the causes for such complexity are the chemically distinct chain end-groups that are the most abundant irregularities in any linear polymer. In this work we demonstrate that chain end induced defects allow polymer glasses to create confined environments capable of hosting small emissive molecules. Using environmentally sensitive luminescent complexes we show that the size of these confinements depends on molecular weight and can dramatically affect the photoluminescence of free or covalently bound emissive complexes. We confirm the impact of chain end confinement on the bulk glass transition in poly(methyl acrylate) and show that commonly observed T<sub>g</sub> changes induced by the chain ends should have a structural origin. Finally, we demonstrate that size and placement of luminescent molecular probes in pMA can dramatically affect the probe luminescence and its temperature dependence suggesting that polymer glass is a highly irregular and complex environment marking its difference with conventional small molecule solvents. Considering the ubiquity of luminescent glassy materials, our work lays down a blueprint for designing them with structural considerations in mind, ones where packing density and chain end size are key factors.

Heat Generation and Flow and Thermal Effects on Optical Spectra in Laser Diode Pumped Thulium-doped Vanadate Crystals

2011 ◽  
Author(s):  
R. Lisiecki ◽  
P. Stachowiak ◽  
A. Jeżowski ◽  
P. Solarz ◽  
G. Dominiak-Dzik ◽  
...  
Keyword(s):  
Laser Diode ◽  
Heat Generation ◽  
Thermal Effects ◽  
Optical Spectra ◽  
Diode Pumped

Thermal effects on the optical spectra of Al2O3:Ti3+

1986 ◽  
Vol 84 (2) ◽  
pp. 662-665 ◽  
Author(s):  
Richard C. Powell ◽  
George E. Venikouas ◽  
Lin Xi ◽  
Jacek K. Tyminski ◽  
Milan R. Kokta
Keyword(s):  
Thermal Effects ◽  
Optical Spectra

ChemInform Abstract: Thermal Effects on the Optical Spectra of Al2O3:Ti3+.

1986 ◽  
Vol 17 (18) ◽  
Author(s):  
R. C. POWELL ◽  
G. E. VENIKOUAS ◽  
L. XI ◽  
J. K. TYMINSKI ◽  
M. R. KOKTA
Keyword(s):  
Thermal Effects ◽  
Optical Spectra

scholarly journals Environmentally Sensitive Luminescence Reveals Spatial Confinement, Dynamics and Their Molecular Weight Dependence in a Polymer Glass

2021 ◽  
Author(s):  
Stephen Picken ◽  
Georgy Filonenko
Keyword(s):  
Molecular Weight ◽  
Molecular Probes ◽  
Key Factors ◽  
Polymer Glasses ◽  
Polymer Glass ◽  
Irregular Structure ◽  
Glassy Materials ◽  
Environmentally Sensitive ◽  
Induced Defects ◽  
The Impact

Polymer glasses have an irregular structure. Among the causes for such complexity are the chemically distinct chain end-groups that are the most abundant irregularities in any linear polymer. In this work we demonstrate that chain end induced defects allow polymer glasses to create confined environments capable of hosting small emissive molecules. Using environmentally sensitive luminescent complexes we show that the size of these confinements depends on molecular weight and can dramatically affect the photoluminescence of free or covalently bound emissive complexes. We confirm the impact of chain end confinement on the bulk glass transition in poly(methyl acrylate) and show that commonly observed T<sub>g</sub> changes induced by the chain ends should have a structural origin. Finally, we demonstrate that size and placement of luminescent molecular probes in pMA can dramatically affect the probe luminescence and its temperature dependence suggesting that polymer glass is a highly irregular and complex environment marking its difference with conventional small molecule solvents. Considering the ubiquity of luminescent glassy materials, our work lays down a blueprint for designing them with structural considerations in mind, ones where packing density and chain end size are key factors.

Thermal Considerations in Lens Regulator Systems

1970 ◽  
Vol 28 ◽  
pp. 358-359
Author(s):  
K.C. Newton
Keyword(s):  
Electron Microscope ◽  
Thermal Effects ◽  
Environmental Control ◽  
Reference Networks ◽  
Better Than

Thermal effects in lens regulator systems have become a major problem with the extension of electron microscope resolution capabilities below 5 Angstrom units. Larger columns with immersion lenses and increased accelerating potentials have made solutions more difficult by increasing the power being handled. Environmental control, component choice, and wiring design provide answers, however. Figure 1 indicates with broken lines where thermal problems develop in regulator systemsExtensive environmental control is required in the sampling and reference networks. In each case, stability better than I ppm/min. is required. Components with thermal coefficients satisfactory for these applications without environmental control are either not available or priced prohibitively.

Direct measurement of electron-diffraction-pattern intensities using an energy loss spectrometer

1989 ◽  
Vol 47 ◽  
pp. 668-669
Author(s):  
A. G. Jackson ◽  
M. Rowe
Keyword(s):  
Thermal Effects ◽  
Dynamic Range ◽  
Scattering Amplitude ◽  
Dynamical Theory ◽  
Site Symmetry ◽  
Proof Of Concept ◽  
Parallel Acquisition ◽  
Kinematic Approximation ◽  
Speed Up ◽  
Structure Calculations

Diffraction intensities from intermetallic compounds are, in the kinematic approximation, proportional to the scattering amplitude from the element doing the scattering. More detailed calculations have shown that site symmetry and occupation by various atom species also affects the intensity in a diffracted beam. [1] Hence, by measuring the intensities of beams, or their ratios, the occupancy can be estimated. Measurement of the intensity values also allows structure calculations to be made to determine the spatial distribution of the potentials doing the scattering. Thermal effects are also present as a background contribution. Inelastic effects such as loss or absorption/excitation complicate the intensity behavior, and dynamical theory is required to estimate the intensity value.The dynamic range of currents in diffracted beams can be 104or 105:1. Hence, detection of such information requires a means for collecting the intensity over a signal-to-noise range beyond that obtainable with a single film plate, which has a S/N of about 103:1. Although such a collection system is not available currently, a simple system consisting of instrumentation on an existing STEM can be used as a proof of concept which has a S/N of about 255:1, limited by the 8 bit pixel attributes used in the electronics. Use of 24 bit pixel attributes would easily allowthe desired noise range to be attained in the processing instrumentation. The S/N of the scintillator used by the photoelectron sensor is about 106 to 1, well beyond the S/N goal. The trade-off that must be made is the time for acquiring the signal, since the pattern can be obtained in seconds using film plates, compared to 10 to 20 minutes for a pattern to be acquired using the digital scan. Parallel acquisition would, of course, speed up this process immensely.

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