Search results for "Fluorescence"

Studies of inelastic cross-section in Rb(7S) + Rb(5S) collisions

1996

The cross section σ = (8 ± 4) × 10−15 cm2 was determined for the Rb(7S) + Rb(5S) → Rb(5D) + Rb(5S) excitation energy transfer process, and the quenching cross section σq = (2 ± 1) × 10−14 cm2 for the Rb(5D) state in collisions with ground state Rb atoms. Applying rubidium quasimolecular asymptotic potential curves at relatively large internuclear distances, a qualitative interpretation of the experimental results is presented. It is shown that the quenching of the Rb(5D) atoms in collisions may be explained by a reversed energy pooling process Rb(5D) + Rb(5S) → Rb(5P) + Rb(5P).

Steady light from quantum dots, at last. But how?

2009

LIF intensity distribution as a deperturbation tool: application to the fully-mixed A1Σ+–b3Π complex of NaRb

2005

Abstract The intensity distribution in the NaRb A 1 Σ + ( v A ′ = 16 , J ′ = 30 ; v A ′ = 18 , J ′ = 66 ) ∼ b 3 Π → X 1 Σ + ( v X ′ ′ = 2 ÷ 44 , J ′ ′ = J ′ ± 1 ) fluorescence series induced by diode laser excitation from the ground state have been measured and directly applied to restore adiabatic potential energy curve for the A-state of the fully-mixed A 1 Σ + – b 3 Π complex. Relative intensities in the long non-diagonal A → X progressions have been proved to be much less influenced by strong spin–orbit interaction than the corresponding term values of the fully coupled A 1 Σ + – b 3 Π complex.

Fast thermometry for trapped ions using dark resonances

2015

We experimentally demonstrate a method to determine the temperature of trapped ions which is suitable for monitoring fast thermalization processes. We show that observing and analyzing the lineshape of dark resonances in the fluorescence spectrum provides a temperature measurement which accurate over a large dynamic range, applied to single ions and small ion crystals. Laser induced fluorescence is detected over a time of only $20\,\mu$s allowing for rapid determination of the ion temperature. In the measurement range of $10^{-1}-10^{+2}\,$mK we reach better than $15\,\%$ accuracy. Tuning the cooling laser to selected resonance features allows for controlling the ion temperatures between $0…

The Sun as a benchmark of flaring activity in stellar coronae

2009

The solar corona is a template to study and understand stellar activity. However the solar corona differs from that of active stars: the Sun has lower X‐ray luminosity, and on average cooler plasma temperatures. Active stellar coronae have a hot peak in their emission measure distribution, EM (T), at 8–20 MK, while the non‐flaring solar corona has a peak at 1–2 MK. In the solar corona significant amounts of plasma at temperature ∼10 MK are observed only during flares.To investigate what is the time‐averaged effect of solar flares we measure the disk‐integrated time‐averaged emission measure, EMF (T), of an unbiased sample of solar flares. To this aim we analyze uninterrupted GOES/XRS light …

Radiative lifetimes of the(1–3)Π1states in NaCs: Experiment and theory

2007

The radiative lifetimes of the $(3)\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}$ and $D(2)\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}$ states of the NaCs molecule have been directly measured in a thermal cell from fluorescence kinetics after modulated laser excitation. The experimental ${\ensuremath{\tau}}_{(3)\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}}^{\mathrm{rad}}$ values of the $(3)\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}({v}^{\ensuremath{'}}∊[3,25];{J}^{\ensuremath{'}}∊[25,106])$ levels decrease from $29\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}21\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$ as the ${v}^{\ensuremath{'}}$ values increase. The measured …

An Active X-Ray Spectrometer for the SELENE-2 Rover

2014

The Active X-ray Spectrometer (AXS) for the Japanese SELENE-2 rover has been proposed for elemental analysis on the lunar surface to measure the major elements: Mg, Al, Si, Ca, Ti, and Fe; the minor elements, Na, K, P, S, Cl, Cr, and Mn and the trace element Ni, all depending on their concentrations at a landing site. The elemental data of the AXS allow us to not only classification but also quantification of surface rocks on the Moon. The AXS is a compact low-weight instrument for elemental analysis based on the principle of X-ray fluorescence spectrometry using an X-ray spectrometer and two (four) pyroelectric crystals as X-Ray Generators (XRG). This paper introduces the current status of…

Fluorescence of rubidium in a submicrometer vapor cell: spectral resolution of atomic transitions between Zeeman sublevels in a moderate magnetic fie…

2005

It is experimentally demonstrated that use of an extremely thin cell (ETC) with the thickness of a Rb atomic vapor column of ∼400 nm allows one to resolve a large number of individual transitions between Zeeman sublevels of the D1 line of 87Rb and 85Rb in the sub-Doppler fluorescence excitation spectra in an external magnetic field of ∼200 G. It is revealed that due to the peculiarities of the Zeeman effect for different hyperfine levels of Rb, all allowed transitions between magnetic sublevels can be clearly resolved for 87RbF_g = 1 --> F_e = 1, 2 and F_g = 2 --> F_e = 1, 2 fluorescence excitation. Also, relatively good spectral resolution can be achieved for 85RbF_g = 2 --> F_e = 2, 3 flu…

Proton-neutron correlations and the longitudinal nuclear response

1988

We study the influence of the proton-neutron correlations, in particular of the tensor ones, on the longitudinal nuclear response. They generate a high-energy tail that we evaluate. We show that this tail produces an apparent quenching of the Coulomb sum rule. The amount of quenching found is significant, although insufficient to explain the totality of the missing strength.

Shifts of the 3D - 4P transitions in different isotopes of positive calcium ions

1997

A sample of stable isotopes containing the masses 40, 42, 43 and 44 was stored under buffer-gas conditions in a Paul ion trap. After population of the metastable 3D levels by spontaneous decay of the laser-excited 4P state we observed laser-induced fluorescence when we scanned a laser across the different 3D - 4P fine-structure lines at 850, 854 and 866 nm. From the Doppler-limited lines of these transitions we deduced the isotope shifts, which are of the order of several GHz due to the large specific mass shift of the metastable 3D levels.