Search results for "electromagnetic [radiation]"
showing 10 items of 873 documents
En-Face differential absorption optical coherence tomography with gold nanorods as the contrast agent
2008
A new variety of nanoparticles showing unique and characteristic optical properties, appeals for its use as contrast agents in medical imaging. Gold nanospheres, nanorods and nanoshells with a silica core are new forms of promising contrast agents which can be tuned to specific absorption or scattering characteristics within the near-infrared (NIR) spectrum ranging from 650 - 1300 nm. They have the ability to be used for both image enhancement and as photosensitive markers due to their well designable scattering and absorption properties. Furthermore, their strong optical absorption permits treatment of malignant cells by photoablation processes, induced when heating them with a matched lig…
Volcanic CO_2 detection with a DFM/OPA-based lidar
2015
The DFM/OPA-based lidar BILLI was used to investigate the volcanic plume released by the hydrothermal vent of Pisciarelli, in the Campi Flegrei volcano. BILLI remotely measured CO2 concentrations in cross-sections of the nearvent plume using the differential absorption technique. To our knowledge, this is the first example of lidar-based measurement of volcanic CO2 . The spatial resolution was 1.5 m and the temporal resolution 20 s. © 2015 Optical Society of America.
Fast tracking of wind speed with a differential absorption LiDAR system: First results of an experimental campaign at Stromboli volcano
2017
Carbon dioxide ( CO 2 ) is considered a precursor gas of volcanic eruptions by volcanologists. Monitoring the anomalous release of this parameter, we can retrieve useful information for the mitigation of volcanic hazards, such as for air traffic security. From a dataset collected during the Stromboli volcano field campaign, an assessment of the wind speed, in both horizontal and vertical paths, performing a fast tracking of this parameter was retrieved. This was determined with a newly designed shot-per-shot differential absorption LiDAR system operated in the near-infrared spectral region due to the simultaneous reconstruction of CO 2 concentrations and wind speeds, using the same sample o…
Scattering and absorption imaging of a highly fractured fluid-filled seismogenetic volume in a region of slow deformation
2020
Regions of slow strain often produce swarm-like sequences, characterized by the lack of a clear mainshock-aftershock pattern. The comprehension of their underlying physical mechanisms is challenging and still debated. We used seismic recordings from the last Pollino swarm (2010–2014) and nearby to separate and map seismic scattering (from P peak-delays) and absorption (from late-time coda-wave attenuation) at different frequencies in the Pollino range and surroundings. High-scattering and high-absorption anomalies are markers of a fluid-filled fracture volume extending from SE to NW (1.5–6 Hz) across the range. With increasing frequency, these anomalies approximately cover the area where t…
The study of time-resolved absorption and luminescence in PbWO4 crystals
2000
Abstract The transient absorption and luminescence under pulsed electron beam excitation were studied for undoped and La3+ doped PbWO4 crystals. The absorption band at ∼1.0 eV is suggested to be due to self-trapped electrons and the absorption band at 3.5 eV may be due to self-trapped holes. The formation of luminescence centers via electron–hole recombination is affected by La3+ in doped crystals. The large fraction of electrons and holes undergoes thermostimulated recombination within geminate pairs and the spatial separation of geminate pairs components is important in recombination process. The intrinsic (blue) luminescence arises in this recombination. The mechanism of La3+ influence o…
Local Structure Studies of Ti for SrTi16O3 and SrTi18O3 by Advanced X-ray Absorption Spectroscopy Data Analysis
2015
Strontium titanate is a model quantum paraelectric in which in the region of dominating quantum statistics the ferroelectric instability is inhibited due to nearly complete compensation of the harmonic contribution into ferroelectric soft mode frequency by the zero-point motion contribution. The enhancement of atomic masses by the substitution of 18O for 16O decreases the zero-point atomic motion and low-T ferroelectricity in SrTi18O3 is realized. In this study we report on the local structure of Ti in SrTi16O3 and SrTi18O3 by Ti K-edge extended x-ray absorption fine structure measurements in temperature range 6 – 300 K.
All-Organic Waveguide Sensor for Volatile Solvent Sensing
2019
This work was supported by ERDF 1.1.1.1 Activity Project Nr. 1.1.1.1/16/A/046 “Application assessment of novel organic materials by prototyping of photonic devices”. We acknowledge Igors MIHAILOVS for valuable discussions.
Time of flight for photon in human skin
2016
The time of flight for photons in human skin was measured using picosecond diode laser. Two different wavelength lasers were used - 405 nm and 510 nm. A difference for time of flight in normal skin and in nevus was observed as well as a difference for different wavelength laser irradiation was observed. For 405 nm laser irradiation the difference was 41 ps while comparison of time of flights skin and nevi using 510 nm irradiation showed a result of 32 ps. Results allow to conclude that the time photon travels in skin might depend on the characteristics of the medium and wavelength of the irradiation. This can be related to known data for light penetration depth in human skin for different w…
Sensitivity of aerosol radiative effects to different mixing assumptions in the AEROPT 1.0 submodel of the EMAC atmospheric-chemistry–climate model
2014
Abstract. The modelling of aerosol radiative forcing is a major cause of uncertainty in the assessment of global and regional atmospheric energy budgets and climate change. One reason is the strong dependence of the aerosol optical properties on the mixing state of aerosol components, such as absorbing black carbon and, predominantly scattering sulfates. Using a new column version of the aerosol optical properties and radiative-transfer code of the ECHAM/MESSy atmospheric-chemistry–climate model (EMAC), we study the radiative transfer applying various mixing states. The aerosol optics code builds on the AEROPT (AERosol OPTical properties) submodel, which assumes homogeneous internal mixing …
In-beam spectroscopic study of $^{244}$Cf
2018
The ground-state rotational band of the neutron-deficient californium ( Z = 98 ) isotope 244 Cf was identified for the first time and measured up to a tentative spin and parity of I π = 20 + . The observation of the rotational band indicates that the nucleus is deformed. The kinematic and dynamic moments of inertia were deduced from the measured γ -ray transition energies. The behavior of the dynamic moment of inertia revealed an up-bend due to a possible alignment of coupled nucleons in high- j orbitals starting at a rotational frequency of about ℏ ω = 0.20 MeV . The results were compared with the systematic behavior of the even-even N = 146 isotones as well as with available theoretical c…