Resonant Light Scattering by Single-Particle Electronic Excitations inn−GaAs

1971 ◽  
Vol 27 (6) ◽  
pp. 317-320 ◽  
Author(s):  
A. Pinczuk ◽  
L. Brillson ◽  
E. Burstein ◽  
E. Anastassakis
Keyword(s):  
Light Scattering ◽  
Single Particle ◽  
Electronic Excitations

Light scattering spectroscopy of Tl-based superconductors: phonon and electronic excitations

1989 ◽  
Vol 162-164 ◽  
pp. 1409-1414 ◽  
Author(s):  
V.B. Timofeev ◽  
A.A. Maksimov ◽  
O.V. Misochko ◽  
I.I. Tartakovskii
Keyword(s):  
Light Scattering ◽  
Electronic Excitations ◽  
Light Scattering Spectroscopy

scholarly journals Single-particle measurements of bouncing particles and in situ collection efficiency from an airborne aerosol mass spectrometer (AMS) with light-scattering detection

2017 ◽  
Vol 10 (10) ◽  
pp. 3801-3820 ◽  
Author(s):  
Jin Liao ◽  
Charles A. Brock ◽  
Daniel M. Murphy ◽  
Donna T. Sueper ◽  
André Welti ◽  
...  
Keyword(s):  
Light Scattering ◽  
Mass Spectrometer ◽  
Single Particle ◽  
Total Mass ◽  
Mass Spectra ◽  
Collection Efficiency ◽  
Aerosol Mass Spectrometer ◽  
Mass Spectral ◽  
Aerosol Mass ◽  
Spectral Signal

Abstract. A light-scattering module was coupled to an airborne, compact time-of-flight aerosol mass spectrometer (LS-AMS) to investigate collection efficiency (CE) while obtaining nonrefractory aerosol chemical composition measurements during the Southeast Nexus (SENEX) campaign. In this instrument, particles scatter light from an internal laser beam and trigger saving individual particle mass spectra. Nearly all of the single-particle data with mass spectra that were triggered by scattered light signals were from particles larger than ∼ 280 nm in vacuum aerodynamic diameter. Over 33 000 particles are characterized as either prompt (27 %), delayed (15 %), or null (58 %), according to the time and intensity of their total mass spectral signals. The particle mass from single-particle spectra is proportional to that derived from the light-scattering diameter (dva-LS) but not to that from the particle time-of-flight (PToF) diameter (dva-MS) from the time of the maximum mass spectral signal. The total mass spectral signal from delayed particles was about 80 % of that from prompt ones for the same dva-LS. Both field and laboratory data indicate that the relative intensities of various ions in the prompt spectra show more fragmentation compared to the delayed spectra. The particles with a delayed mass spectral signal likely bounced off the vaporizer and vaporized later on another surface within the confines of the ionization source. Because delayed particles are detected by the mass spectrometer later than expected from their dva-LS size, they can affect the interpretation of particle size (PToF) mass distributions, especially at larger sizes. The CE, measured by the average number or mass fractions of particles optically detected that had measurable mass spectra, varied significantly (0.2–0.9) in different air masses. The measured CE agreed well with a previous parameterization when CE > 0.5 for acidic particles but was sometimes lower than the minimum parameterized CE of 0.5.

scholarly journals Intercomparison study and optical asphericity measurements of small ice particles in the CERN CLOUD experiment

2017 ◽  
Vol 10 (9) ◽  
pp. 3231-3248 ◽  
Author(s):  
Leonid Nichman ◽  
Emma Järvinen ◽  
James Dorsey ◽  
Paul Connolly ◽  
Jonathan Duplissy ◽  
...  
Keyword(s):  
Light Scattering ◽  
Single Particle ◽  
Optical Measurements ◽  
Optical Observations ◽  
Atmospheric Measurements ◽  
Optical Probes ◽  
Cloud Particle ◽  
Ice Particles ◽  
Cloud Particles ◽  
Ice Fraction

Abstract. Optical probes are frequently used for the detection of microphysical cloud particle properties such as liquid and ice phase, size and morphology. These properties can eventually influence the angular light scattering properties of cirrus clouds as well as the growth and accretion mechanisms of single cloud particles. In this study we compare four commonly used optical probes to examine their response to small cloud particles of different phase and asphericity. Cloud simulation experiments were conducted at the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at European Organisation for Nuclear Research (CERN). The chamber was operated in a series of multi-step adiabatic expansions to produce growth and sublimation of ice particles at super- and subsaturated ice conditions and for initial temperatures of −30, −40 and −50 °C. The experiments were performed for ice cloud formation via homogeneous ice nucleation. We report the optical observations of small ice particles in deep convection and in situ cirrus simulations. Ice crystal asphericity deduced from measurements of spatially resolved single particle light scattering patterns by the Particle Phase Discriminator mark 2 (PPD-2K, Karlsruhe edition) were compared with Cloud and Aerosol Spectrometer with Polarisation (CASPOL) measurements and image roundness captured by the 3View Cloud Particle Imager (3V-CPI). Averaged path light scattering properties of the simulated ice clouds were measured using the Scattering Intensity Measurements for the Optical detectioN of icE (SIMONE) and single particle scattering properties were measured by the CASPOL. We show the ambiguity of several optical measurements in ice fraction determination of homogeneously frozen ice in the case where sublimating quasi-spherical ice particles are present. Moreover, most of the instruments have difficulties of producing reliable ice fraction if small aspherical ice particles are present, and all of the instruments cannot separate perfectly spherical ice particles from supercooled droplets. Correlation analysis of bulk averaged path depolarisation measurements and single particle measurements of these clouds showed higher R2 values at high concentrations and small diameters, but these results require further confirmation. We find that none of these instruments were able to determine unambiguously the phase of the small particles. These results have implications for the interpretation of atmospheric measurements and parametrisations for modelling, particularly for low particle number concentration clouds.

scholarly journals Detection of tar brown carbon with a single particle soot photometer (SP2)

2019 ◽  
Vol 19 (24) ◽  
pp. 15673-15690 ◽  
Author(s):  
Joel C. Corbin ◽  
Martin Gysel-Beer
Keyword(s):  
Light Scattering ◽  
Single Particle ◽  
Measurement Techniques ◽  
Particulate Material ◽  
Infrared Light ◽  
Brown Carbon ◽  
Soot Mass ◽  
Laser Induced Incandescence ◽  
Definition Of ◽  
Unique Signal

Abstract. We investigate the possibility that the refractory, infrared-light-absorbing carbon particulate material known as “tarballs” or tar brown carbon (tar brC) generates a unique signal in the scattering and incandescent detectors of a single particle soot photometer (SP2). As recent studies have defined tar brC in different ways, we begin by reviewing the literature and proposing a material-based definition of tar. We then show that tar brC results in unique SP2 signals due to a combination of complete or partial evaporation, with no or very little incandescence. Only a subset of tar brC particles exhibited detectable incandescence (70 % by number); for these particles the ratio of incandescence to light scattering was much lower than that of soot black carbon (BC). At the time of incandescence the ratio of light scattering to incandescence from these particles was up to 2-fold greater than from soot (BC). In our sample, where the mass of tar was 3-fold greater than the mass of soot, this led to a bias of <5 % in SP2-measured soot mass, which is negligible relative to calibration uncertainties. The enhanced light scattering of tar is interpreted as being caused by tar being more amorphous and less graphitic than soot BC. The fraction of the tar particle which does incandesce was likely formed by thermal annealing during laser heating. These results indicate that laser-induced incandescence, as implemented in the SP2, is the only BC measurement technique which can quantify soot BC concentrations separately from tar while also potentially providing real-time evidence for the presence of tar. In contrast, BC measurement techniques based on thermal–optical (EC: elemental carbon) and absorption (eBC: equivalent BC) measurements cannot provide such distinctions. The optical properties of our tar particles indicate a material similarity to the tar particles previously reported in the literature. However, more- and less-graphitized tar samples have also been reported, which may show stronger and weaker SP2 responses, respectively.

Inelastic light scattering by spin-density, charge-density, and single-particle excitations in GaAs quantum wires

1994 ◽  
Vol 49 (20) ◽  
pp. 14778-14781 ◽  
Author(s):  
A. Schmeller ◽  
A. R. Goñi ◽  
A. Pinczuk ◽  
J. S. Weiner ◽  
J. M. Calleja ◽  
...  
Keyword(s):  
Light Scattering ◽  
Charge Density ◽  
Spin Density ◽  
Single Particle ◽  
Quantum Wires ◽  
Inelastic Light Scattering
Sign in / Sign up

Export Citation Format

Share Document