16 research outputs found
Efficiency of photodesorption of Rb atoms collected on polymer organic film in vapor-cell
The efficiency of photodesorption of Rb atoms previously collected on polymer
organic film has been studied in detail. This study was carried out in a Pyrex
glass cell of which the inner surface was covered with (poly)dimethylsiloxane
(PDMS) film and illuminated by a powerful flash lamp. The desorption dynamic of
the Rb atoms density in the cell caused by the illumination and percentage of
desorbed atoms was studied by using of Rb resonance lamp and free running diode
laser as sources of probing light. It was determined that 85 percent collected
chemical active Rb atoms and stored during 16 seconds in the closed cell, 75
percent in the pumped cell can be desorbed by single flash of the lamp. The
number of stored atoms decays with a characteristic time of 60 min in isolated
cell and with a time 12.4 minutes in a pumped cell. We believe that this
efficient method of collection and fast realization of atoms or molecules could
be used for enhancement of sensitivity of existed sensors for the trace
detection of various elements (including toxic or radioactive ones) which is
important to environmental applications, medicine or in geology. The effect
might help to construct an efficient light-driven atomic source for a
magneto-optical trap in a case of extremely low vapor density or very weak flux
of atoms, such as artificial radioactive alkali atoms.Comment: 9 pages, 9 figures; accepted for publication in EPJ
NEW PERMAFROST FEATURE – DEP CRATER IN CENTRAL YAMAL (WEST SIBERIA, RUSIA) AS A RESPONSE TO LOCAL CLIMATE FLUCTUATIONS
This paper is based on field data obtained during short visits to a newly formed permafrost feature in a form of relatively narrow, deep crater. Excluding impossible and improbable versions of the crater’s development, the authors conclude that it originated from warmerground temperatures and an increase in unfrozen water content, leading to an increase in pressure from gas emissions from permafrost and ground ice. This conclusion is also supported by known processes in the palaeo-geography of Yamal lakes and recent studies of gas-hydrate behavior and subsea processes in gas-bearing provinces
Boundary control and observation of some one-dimensional vibrating structures : regularity and stabilization
SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : 14802 E, issue : a.1991 n.1382 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
Plasmon Controlled Exciton Fluorescence of Molecular Aggregates
In the present work controlled plasmon
enhanced fluorescence of thiacyanine dye J-aggregates in water solution
has been demonstrated. To control a distance between J-aggregates
and silver nanoparticles the latter have been covered by a polymer
shell of variable thickness using the layer-by-layer assembly method.
The best 2-fold fluorescence enhancement has been observed for the
16 nm thick polymer shell. Transmission electron microscopy (TEM)
images have revealed an insufficient contact between J-aggregates
and NPs that could be the main reason for the small fluorescence enhancement.
Experimental results have been described using a model of two-level
system affected by the local plasmon resonances field. According to
the model more than 20-fold enhancement of J-aggregates fluorescence
could be expected under optimal conditions. Besides, strong fluorescence
enhancement dependence on an exciton coherence length has been predicted.
According to it, significant fluorescence response should be observed
for metal nanoparticles interacting J-aggregates with large exciton
coherence length such as pseudoisocyanine J-aggregates and some others
Corporate Governance: Impulses from the Middle East
Corporate governance, Corporate leadership, Intercultural management, Transcultural management, G34,