1,279 research outputs found
Room Temperature Electrical Detection of Spin Coherence in C60
An experimental demonstration of electrical detection of coherent spin motion
of weakly coupled, localized electron spins in thin Fullerene C60 films at room
temperature is presented. Pulsed electrically detected magnetic resonance
experiments on vertical photocurrents through Al/C60/ZnO samples showed that an
electron spin Rabi oscillation is reflected by transient current changes. The
nature of possible microscopic mechanisms responsible for this spin to charge
conversion as well as its implications for the readout of endohedral Fullerene
(N@C60) spin qubits are discussed.Comment: 4 pages, 3 figure
CW and pulsed electrically detected magnetic resonance spectroscopy at 263 GHz/12 T on operating amorphous silicon solar cells
Here we describe a new high frequency/high field continuous wave and pulsed
electrically detected magnetic resonance (CW EDMR and pEDMR) setup, operating
at 263 GHz and resonance fields between 0 and 12 T. Spin dependent transport in
illuminated hydrogenated amorphous silicon p-i-n solar cells at 5 K and 90 K
was studied by in operando 263 GHz CW and pEDMR alongside with complementary
X-band CW EDMR. Benefiting from the superior resolution at 263 GHz, we were
able to better resolve EDMR signals originating from spin dependent hopping and
recombination processes. 5 K EDMR spectra were found to be dominated by
conduction and valence band tale states involved in spin dependent hopping,
with additional contributions from triplet exciton states. 90 K EDMR spectra
could be assigned to spin pair recombination involving conduction band tail
states and dangling bonds as dominating spin dependent transport process, with
additional contributions from valence band tail and triplet exciton states.Comment: 8 pages, 4 figure
Transport and recombination through weakly coupled localized spin pairs in semiconductors during coherent spin excitation
Semi-analytical predictions for the transients of spin-dependent transport
and recombination rates through localized states in semiconductors during
coherent electron spin excitation are made for the case of weakly spin-coupled
charge carrier ensembles. The results show that the on-resonant Rabi frequency
of electrically or optically detected spin-oscillation doubles abruptly as the
strength of the resonant microwave field gamma B_1 exceeds the Larmor frequency
separation within the pair of charge carrier states between which the transport
or recombination transition takes place. For the case of a Larmor frequency
separation of the order of gamma B_1 and arbitrary excitation frequencies, the
charge carrier pairs exhibit four different nutation frequencies. From the
calculations, a simple set of equations for the prediction of these frequencies
is derived
Using rapid scan EPR to improve the detection limit of quantitative EPR by more than one order of magnitude
X band rapid scan EPR was implemented on a commercially available Bruker ELEXSYS E580 spectrometer. Room temperature rapid scan and continuous wave EPR spectra were recorded for amorphous silicon powder samples. By comparing the resulting signal intensities the feasibility of performing quantitative rapid scan EPR is demonstrated. For different hydrogenated amorphous silicon samples, rapid scan EPR results in signal to noise improvements by factors between 10 and 50. Rapid scan EPR is thus capable of improving the detection limit of quantitative EPR by at least one order of magnitude. In addition, we provide a recipe for setting up and calibrating a conventional pulsed and continuous wave EPR spectrometer for rapid scan EP
Large Interstellar Polarisation Survey. LIPS I: FORS2 spectropolarimetry in the Southern Hemisphere
Polarimetric studies of light transmitted through interstellar clouds may
give constraints on the properties of the interstellar dust grains.
Traditionally, broadband linear polarisation (BBLP) measurements have been
considered an important diagnostic tool for the study of the interstellar dust,
while comparatively less attention has been paid to spectropolarimetric
measurements. However, spectropolarimetry may offer stronger constraints than
BBLP, for example by revealing narrowband features, and by allowing us to
distinguish the contribution of dust from the contribution of interstellar gas.
Therefore, we have decided to carry out a Large Interstellar Polarisation
Survey (LIPS) using spectropolarimetric facilities in both hemispheres. Here we
present the results obtained in the Southern Hemisphere with the FORS2
instrument of the ESO Very Large Telescope. Our spectra cover the wavelength
range 380--950\,nm at a spectral resolving power of about 880. We have produced
a publicly available catalogue of 127 linear polarisation spectra of 101
targets. We also provide the Serkowski-curve parameters, as well as the
wavelength gradient of the polarisation position angle for the interstellar
polarisation along 76 different lines of sight. In agreement with previous
literature, we found that the best-fit parameters of the Serkowski-curve are
not independent of each other. However, the relationships that we obtained are
not always consistent with what was found in previous studies.Comment: Accepted by A&A (replaced on 12 October 2017 simply to correct a
Metadata error
Upwelling events, coastal offshore exchange, links to biogeochemical processes - Highlights from the Baltic Sea Sciences Congress at Rostock University, Germany, 19-22 March 2007
The Baltic Sea Science Congress was held at Rostock University, Germany, from 19 to 22 March 2007. In the session entitled"Upwelling events, coastal offshore exchange, links to biogeochemical processes" 20 presentations were given,including 7 talks and 13 posters related to the theme of the session.This paper summarises new findings of the upwelling-related studies reported in the session. It deals with investigationsbased on the use of in situ and remote sensing measurements as well as numerical modelling tools. The biogeochemicalimplications of upwelling are also discussed.Our knowledge of the fine structure and dynamic considerations of upwelling has increased in recent decades with the advent ofhigh-resolution modern measurement techniques and modelling studies. The forcing and the overall structure, duration and intensity ofupwelling events are understood quite well. However, the quantification of related transports and the contribution to the overall mixingof upwelling requires further research. Furthermore, our knowledge of the links between upwelling and biogeochemical processes is stillincomplete. Numerical modelling has advanced to the extent that horizontal resolutions of c. 0.5 nautical miles can now be applied,which allows the complete spectrum of meso-scale features to be described. Even the development of filaments can be describedrealistically in comparison with high-resolution satellite data.But the effect of upwelling at a basin scale and possible changes under changing climatic conditions remain open questions
Thermite-for-Demise (T4D): Preliminary Assessment on the Effects of a Thermite Charge in Arc-Heated Wind Tunnel Experiments
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