Time-Resolved Two-Dimensional Temperature Measurement From Acetylene-Oxygen Flame Using Chemical Seeding Spectrocamera

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Hiroyuki Oyama ◽  
Joe Kayahana ◽  
Shigeo Yatsu ◽  
Kuniyuki Kitagawa ◽  
Ashwani K. Gupta
Keyword(s):  
Temperature Distribution ◽  
Image Intensifier ◽  
Video Camera ◽  
Spectroscopic Technique ◽  
Time Resolved ◽  
Industrial Sectors ◽  
Precise Knowledge ◽  
Band Pass ◽  
A Charge ◽  
Almost All

Precise knowledge on temperature and its fluctuation in combustion systems are among the important energy issues in almost all industrial sectors, energy conversion and power fields. In this study, a spectroscopic technique is used to measure the time-resolved temperature distribution by a comparatively simple optical system that involved two band-pass filters (BPF), and a charge-coupled device with image intensifier (ICCD) video camera. The system was assembled and applied to an acetylene-oxygen premixed flame that are widely used for welding purposes because of very high temperature in such flames. The temperature distribution and its fluctuation directly impact the quality of soldering. The results provided direct visualization of temperature and its fluctuation in the flames that are conjectured to emanate from thermal and hydrodynamic phenomena from chemical reactions in the flame and interaction with surrounding air.

scholarly journals Video Techniques for Observation of the Leonid Storms

1998 ◽  
Vol 11 (2) ◽  
pp. 1017-1019 ◽  
Author(s):  
R.L. Hawkes
Keyword(s):  
Spatial Resolution ◽  
Temporal Resolution ◽  
Image Intensifier ◽  
High Sensitivity ◽  
Video Camera ◽  
Third Generation ◽  
Charge Coupled Device ◽  
A Charge ◽  
Video Detector ◽  
Current Systems

Video techniques, which provide high sensitivity, portability, moderate spatial resolution and excellent temporal resolution promise to be one of the most valuable methods for study of the forthcoming Leonid storm(s). While an unintensified video camera will detect very bright meteors (typically about 0 magnitude), some sort of image intensifier is needed to attain high meteor rates. Most current systems use a second or third generation microchannel plate (MCP) image intensifier lens or fibre-optically coupled to a charge coupled device (CCD) video detector.

Sectoral Analysis of Foreign Direct Investment in India During First Generation Reform Period

2015 ◽  
Vol 4 (2) ◽  
Author(s):  
Manoj Kumar Sinha
Keyword(s):  
First Generation ◽  
Correlation Matrices ◽  
Foreign Investors ◽  
Industrial Policies ◽  
Sectoral Analysis ◽  
Industrial Sectors ◽  
Reform Period ◽  
Service Sectors ◽  
Almost All ◽  
Rank Dominance

Since 1991, India has cautiously and slowly opened almost all the sectors, except a few related to strategic importance, for foreign investors. Degree of openness of various industrial sectors for FDI has been increased to the extent of 100 percent by consistently liberalizing industrial policies of the sectors. The purpose of the paper is to study pattern and trends of sectoral distribution of FDI within the background of the first generation reforms and liberalized industrial policies during 1991-2001. The paper has used series of the dynamics and stylistic indices and statistical tools such as three level indices, index of rank dominance, and correlation matrices for explaining the pattern of FDI distribution across sectors during 1991-2001. The results show that electrical, transportation, chemical, telecommunication, and service sectors are most dominating sectors and represent almost 75 percent of total FDI received during 1991-2001. Index of rank dominance indicates distribution of FDI across the sectors is top heavy.

scholarly journals Probing the interplay between lattice dynamics and short-range magnetic correlations in CuGeO3 with femtosecond RIXS

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
E. Paris ◽  
C. W. Nicholson ◽  
S. Johnston ◽  
Y. Tseng ◽  
M. Rumo ◽  
...  
Keyword(s):  
Short Range ◽  
Degrees Of Freedom ◽  
Time Resolved ◽  
Model Calculations ◽  
Spin Correlations ◽  
Singlet Exciton ◽  
Magnetic Correlations ◽  
Local Lattice ◽  
Frustrated Systems ◽  
A Charge

AbstractInvestigations of magnetically ordered phases on the femtosecond timescale have provided significant insights into the influence of charge and lattice degrees of freedom on the magnetic sub-system. However, short-range magnetic correlations occurring in the absence of long-range order, for example in spin-frustrated systems, are inaccessible to many ultrafast techniques. Here, we show how time-resolved resonant inelastic X-ray scattering (trRIXS) is capable of probing such short-ranged magnetic dynamics in a charge-transfer insulator through the detection of a Zhang–Rice singlet exciton. Utilizing trRIXS measurements at the O K-edge, and in combination with model calculations, we probe the short-range spin correlations in the frustrated spin chain material CuGeO3 following photo-excitation, revealing a strong coupling between the local lattice and spin sub-systems.

scholarly journals A time-domain phase diagram of metastable states in a charge ordered quantum material

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jan Ravnik ◽  
Michele Diego ◽  
Yaroslav Gerasimenko ◽  
Yevhenii Vaskivskyi ◽  
Igor Vaskivskyi ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Time Domain ◽  
Metastable States ◽  
Scanning Tunneling ◽  
Photon Density ◽  
Tunneling Microscopy ◽  
Equilibrium Conditions ◽  
Time Resolved ◽  
A Charge ◽  
Non Equilibrium

AbstractMetastable self-organized electronic states in quantum materials are of fundamental importance, displaying emergent dynamical properties that may be used in new generations of sensors and memory devices. Such states are typically formed through phase transitions under non-equilibrium conditions and the final state is reached through processes that span a large range of timescales. Conventionally, phase diagrams of materials are thought of as static, without temporal evolution. However, many functional properties of materials arise as a result of complex temporal changes in the material occurring on different timescales. Hitherto, such properties were not considered within the context of a temporally-evolving phase diagram, even though, under non-equilibrium conditions, different phases typically evolve on different timescales. Here, by using time-resolved optical techniques and femtosecond-pulse-excited scanning tunneling microscopy (STM), we track the evolution of the metastable states in a material that has been of wide recent interest, the quasi-two-dimensional dichalcogenide 1T-TaS2. We map out its temporal phase diagram using the photon density and temperature as control parameters on timescales ranging from 10−12 to 103 s. The introduction of a time-domain axis in the phase diagram enables us to follow the evolution of metastable emergent states created by different phase transition mechanisms on different timescales, thus enabling comparison with theoretical predictions of the phase diagram, and opening the way to understanding of the complex ordering processes in metastable materials.

scholarly journals Synthesis and Photobehavior of a NewDehydrobenzoannulene-Based HOF with Fluorine Atoms: From Solution to Single Crystals Observation

2021 ◽  
Vol 22 (9) ◽  
pp. 4803
Author(s):  
Eduardo Gomez ◽  
Ichiro Hisaki ◽  
Abderrazzak Douhal
Keyword(s):  
Charge Transfer ◽  
Single Crystals ◽  
Parent Compound ◽  
Time Resolved ◽  
Strong Basis ◽  
Triplet Structure ◽  
Carboxylic Groups ◽  
Potential Applications ◽  
A Charge ◽  
Further Development

Hydrogen-bonded organic frameworks (HOFs) are the focus of intense scientific research due their potential applications in science and technology. Here, we report on the synthesis, characterization, and photobehavior of a new HOF (T12F-1(124TCB)) based on a dehydrobenzoannulene derivative containing fluorine atoms (T12F-COOH). This HOF exhibits a 2D porous sheet, which is hexagonally networked via H-bonds between the carboxylic groups, and has an interlayers distance (4.3 Å) that is longer than that of a typical π–π interaction. The presence of the fluorine atoms in the DBA molecular units largely increases the emission quantum yield in DMF (0.33, T12F-COOH) when compared to the parent compound (0.02, T12-COOH). The time-resolved dynamics of T12F-COOH in DMF is governed by the emission from a locally excited state (S1, ~ 0.4 ns), a charge-transfer state (S1(CT), ~ 2 ns), and a room temperature emissive triplet state (T1, ~ 20 ns), in addition to a non-emissive triplet structure with a charge-transfer character (T1(CT), τ = 0.75 µs). We also report on the results using T12F-ester. Interestingly, FLIM experiments on single crystals unravel that the emission lifetimes of the crystalline HOF are almost twice those of the amorphous ones or the solid T12F-ester sample. This shows the relevance of the H-bonds in the photodynamics of the HOF and provides a strong basis for further development and study of HOFs based on DBAs for potential applications in photonics.

scholarly journals The role of spin in the degradation of organic photovoltaics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ivan Ramirez ◽  
Alberto Privitera ◽  
Safakath Karuthedath ◽  
Anna Jungbluth ◽  
Johannes Benduhn ◽  
...  
Keyword(s):  
Transient Absorption ◽  
Bulk Heterojunction ◽  
Critical Factor ◽  
Model Systems ◽  
Transient Absorption Spectroscopy ◽  
Triplet States ◽  
Paramagnetic Resonance ◽  
Time Resolved ◽  
A Charge

AbstractStability is now a critical factor in the commercialization of organic photovoltaic (OPV) devices. Both extrinsic stability to oxygen and water and intrinsic stability to light and heat in inert conditions must be achieved. Triplet states are known to be problematic in both cases, leading to singlet oxygen production or fullerene dimerization. The latter is thought to proceed from unquenched singlet excitons that have undergone intersystem crossing (ISC). Instead, we show that in bulk heterojunction (BHJ) solar cells the photo-degradation of C60 via photo-oligomerization occurs primarily via back-hole transfer (BHT) from a charge-transfer state to a C60 excited triplet state. We demonstrate this to be the principal pathway from a combination of steady-state optoelectronic measurements, time-resolved electron paramagnetic resonance, and temperature-dependent transient absorption spectroscopy on model systems. BHT is a much more serious concern than ISC because it cannot be mitigated by improved exciton quenching, obtained for example by a finer BHJ morphology. As BHT is not specific to fullerenes, our results suggest that the role of electron and hole back transfer in the degradation of BHJs should also be carefully considered when designing stable OPV devices.

scholarly journals Intermittent maser flare around the high-mass young stellar object G353.273+0.641

2012 ◽  
Vol 8 (S287) ◽  
pp. 98-102
Author(s):  
Kazuhito Motogi ◽  
Kazuo Sorai ◽  
Kenta Fujisawa ◽  
Koichiro Sugiyama ◽  
Mareki Honma
Keyword(s):  
Light Curve ◽  
Small Area ◽  
Linear Acceleration ◽  
High Mass ◽  
Velocity Range ◽  
Time Resolved ◽  
Almost All ◽  
Maser Sources ◽  
Water Maser

AbstractThe water maser site associated with G353.273+0.641 is classified as a dominant blueshifted H2O maser, which shows an extremely wide velocity range (± 100 km s−1) with almost all flux concentrated in the highly blueshifted emission. The previous study has proposed that this peculiar H2O maser site is excited by a pole-on jet from high mass protostellar object. We report on the monitoring of 22-GHz H2O maser emission from G353.273+0.641 with the VLBI Exploration of Radio Astrometry (VERA) and the Tomakamai 11-m radio telescope. Our VLBI imaging has shown that all maser features are distributed within a very small area of 200 × 200 au2, in spite of the wide velocity range (> 100 km s−1). The light curve obtained by weekly single-dish monitoring shows notably intermittent variation. We have detected three maser flares during three years. Frequent VLBI monitoring has revealed that these flare activities have been accompanied by a significant change of the maser alignments. We have also detected synchronized linear acceleration (−5 km s−1yr−1) of two isolated velocity components, suggesting a lower-limit momentum rate of 10−3 M⊙ km s−1yr−1 for the maser acceleration. All our results support the previously proposed pole-on jet scenario, and finally, a radio jet itself has been detected in our follow-up ATCA observation. If highly intermittent maser flares directly reflect episodic jet-launchings, G353.273+0.641 and similar dominant blueshifted water maser sources can be suitable targets for a time-resolved study of high mass protostellar jet.

scholarly journals Ultrafast manipulation of mirror domain walls in a charge density wave

2018 ◽  
Vol 4 (10) ◽  
pp. eaau5501 ◽  
Author(s):  
Alfred Zong ◽  
Xiaozhe Shen ◽  
Anshul Kogar ◽  
Linda Ye ◽  
Carolyn Marks ◽  
...  
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Room Temperature ◽  
Domain Walls ◽  
Density Wave ◽  
Charge Ordering ◽  
Time Resolved ◽  
Insulator Metal Transition ◽  
Femtosecond Light Pulse ◽  
A Charge

Domain walls (DWs) are singularities in an ordered medium that often host exotic phenomena such as charge ordering, insulator-metal transition, or superconductivity. The ability to locally write and erase DWs is highly desirable, as it allows one to design material functionality by patterning DWs in specific configurations. We demonstrate such capability at room temperature in a charge density wave (CDW), a macroscopic condensate of electrons and phonons, in ultrathin 1T-TaS2. A single femtosecond light pulse is shown to locally inject or remove mirror DWs in the CDW condensate, with probabilities tunable by pulse energy and temperature. Using time-resolved electron diffraction, we are able to simultaneously track anti-synchronized CDW amplitude oscillations from both the lattice and the condensate, where photoinjected DWs lead to a red-shifted frequency. Our demonstration of reversible DW manipulation may pave new ways for engineering correlated material systems with light.

scholarly journals Development of an experimental apparatus to observe ultrafast phenomena by tender X-ray absorption spectroscopy at PAL-XFEL

2022 ◽  
Vol 29 (1) ◽  
Author(s):  
Yujin Kim ◽  
Daewoong Nam ◽  
Rory Ma ◽  
Sangsoo Kim ◽  
Myung-jin Kim ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Spectroscopic Technique ◽  
Ultrafast Dynamics ◽  
Electronic Information ◽  
Time Resolved ◽  
X Ray ◽  
Experimental Apparatus ◽  
Technical Achievement ◽  
X Ray Absorption ◽  
Pal Xfel

Understanding the ultrafast dynamics of molecules is of fundamental importance. Time-resolved X-ray absorption spectroscopy (TR-XAS) is a powerful spectroscopic technique for unveiling the time-dependent structural and electronic information of molecules that has been widely applied in various fields. Herein, the design and technical achievement of a newly developed experimental apparatus for TR-XAS measurements in the tender X-ray range with X-ray free-electron lasers (XFELs) at the Pohang Accelerator Laboratory XFEL (PAL-XFEL) are described. Femtosecond TR-XAS measurements were conducted at the Ru L 3-edge of well known photosensitizer tris(bipyridine)ruthenium(II) chloride ([Ru(bpy)3]2+) in water. The results indicate ultrafast photoinduced electron transfer from the Ru center to the ligand, which demonstrates that the newly designed setup is applicable for monitoring ultrafast reactions in the femtosecond domain.

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