On charged impurity structures in liquid helium

The thermoluminescence spectra of impurity-helium condensates (IHC) submerged in superfluid helium have been observed for the first time. Thermoluminescence of impurity-helium condensates submerged in superfluid helium is explained by neutralization reactions occurring in impurity nanoclusters. Optical spectra of excited products of neutralization reactions between nitrogen cations and thermoactivated electrons were rather different from the spectra observed at higher temperatures, when the luminescence due to nitrogen atom recombination dominates. New results on current detection during the IHC destruction are presented. Two different mechanisms of nanocluster charging are proposed to describe the phenomena observed during preparation and warmup of IHC samples in bulk superfluid helium, and destruction of IHC samples out of liquid helium

ODMR OF ATOMS TRAPPED IN IMPURITY-HELIUM SOLID.aSOLID.^{a}

$^{a}$Supported by RFBR Projects 98-03-33095, 98-03-32283, 99-03-33261Author Institution: Institute of Energy Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region, Russia; A.F. Ioffe Physico-Technical Institute, St.Petersburg, 194021, Russia; Institute of Applied Physics, Bonn University, Bonn, GermanyMetastable $N(^{2} D)$ atoms are stabilized in an aerogel-like medium, soaked by superfluid helium (HeII), and called Impurity. Helium Solid (IHS), showing strong thermoluminescence in the rage of 1.4 to 4.0 K on the $^{2} D,^{-4}S$ transition (523 nm). Even slight increase in temperature (less than 100 mK) leads to significant rise in luminescence. We used IHS as a specific optical bolometer for monitoring of magnetic resonance (ODMR) of paramagnetic atoms, trapped in IHS and detected for the first time ODMR of ground state $N(^{4}S)$ atoms upon CW microwave incident on the sample and slow sweep of magnetic field. On passing through resonance the sample absorbed microwave radiation and, as a result of spin-lattice relaxation was heated large enough for excitation of luminescence and optical detection of magnetic resonance. Recently we have managed to excite blue luminescence of Kr- and Ar- IHS samples, containing diluted amounts of atomic nitrogen by applying a short heat pulses to the sample directly in Hell. The observed luminescence was found to decay at $\lambda 427$ nm with characteristic time $\tau$ less than 10 msec. We have been improving the sensitivity of this ODMR approach by employing a pulsed microwave radiation with subsequent synchronous detection of luminescence. The method proposed is expected to be universal for optical monitoring of magnetic resonance of any paramagnetic species, trapped in IHS due to non-specific nature of excitation of luminescence

OBSERVATION OF LUMINESCENCE SPECTRA OF KrD RYDBERG MOLECULE AT LOW (40K) TEMPERATURE

$^{a}$ I. Dabrowski, D. A. Sadovskii, Molecular Physics, 81(2), 291, (1994).Author Institution: Institute for Energy Problems of Chemical PhysicsThe luminescence spectra of KrD Rydberg molecule in spectral range from 400 nm to 800 nm in gas phase at low temperatures (40k) were observed for the first time by means of original experimental technique. In this method two gas jets were intersected over the surface of superfluid helium (temperature 1.5K, pressure of helium vapor 10 torr). Gas mixture of He with 1-5frequency electrodeless discharge. The resulting luminescent jet was introduced in a helium cryostat and crossed by a stream of $H_{2}$ or $D_{2}$ molecules to produces RgH or RgD. First experiments with Kr and $D_{2}$ were carried out. A number of bands observed in the luminescence spectra was assinged to KrD extensively studied by Dabrowski et al. $^{a}$. The most pronounced bands observed at 515 nm and 773 nm originate from 4d state and correspond to transitions to 5p states. Transitions from the np complexes were also identified but their intensity were much weaker. Near 483 nm there was rather broad band assigned to transitions from nf complexes. The luminescence spectra of nitrogen molecules and ions, and CN radicals at such low temperatures were also studied and a number of peculiarities in the spectra were observed. These results will be presented as well

LOW TEMPERATURE (∼20K)(\sim 20K) INTRAMOLECULAR ENERGY TRANSFER IN GAS PHASE EVIDENCED BY LUMINESCENCE OF N2,N+2N_{2}, {N^{+}}_{2}, AND CN.

1. E.B. Gordon, A.A.Pelmenev, O.F. Pugachev and V.V.Khmelenko, Chem. Phys. 61(1,2), 35-41, 1981. 2. E.B. Gordon, M.V. Martynenko, A.A. Pelmenev, O.F. Pugachev and V.V. Khmelenko, Khimicheskay Fizika, 13(3), 15-28, 1994, (in Russian).Author Institution: Institute for Energy Problems of Chemical Physics, 1142432, Chernogolovka, Moscow Region, Russia.Gas phase luminescence spectra of N_{2} (1^{+}-system), (N^{+}}_{2} (1^{+}-system), and CN (Red system) in the temperature range 180K - 20K have been studied in the frame of original experimental approach [1] consisting in injection of helium gas jet containing the exposed to HF discharge admixtures under investigation into the cryostat with superfluid helium $(T \sim 1.5K)$. At low temperatures together with strong suppression of rotational structure the dramatic changes in the vibronic bands intensity (some bands almost completely disappear) are observed [2]. For all vibrational levels from which emission is temperature sensitive there are quasiresonant $(\Delta {\rm E} < 100 cm^{-1})$ vibrational levels belonging to another electronic states of the same species. So the effect has been explained by effective energy transfer between the electronic states induced by collisions with cold helium atoms $([He] \sim 10^{-19} cm^{-3})$. The emission bands intensity is determined by mutual disposition of the interacting levels. Its decrease or increase depend on whether exothermic or endothermic, respectively, transition from emitting level to neighboring one. Observed phenomena provide new opportunities for accurate testing the mutual disposition of different electronic states in diatomics as well as for study of intersystem collisional induced processes

COOPERATIVE EFFECTS IN OPTICAL AND ESR SPECTROSCOPY OF NITROGEN ATOMS ISOLATED BY SOLIDIFICATED HELIUM

1. E.B. Gordon, V.V. Khmelenko, A.A. Pelmenev, E.A. Popov and O.P. Pugachev, Chem. Phys. Lett. 155(3), 301-304 (1989). 2. R.E. Boltnev, E.B. Gordon, V.V. Khmelenko, A.A. Pelmenev, I.N. Kusliniskaya, M.V. Martynenko, E.A. Popov and A.V. Shestakov, Chem. Phys. 189(2), 367-382 (1994). 3. R.E. Boltnev, E.B. Gordon, V.V. Khmelenko, M.B. Martynenko, A.A. Pelmenev, E.A. Popov and A.F. Shestakov, J. Chim. Phys. 92(2), 362-383 (1995).Author Institution: Institute for Energy Problems of Chemical Physics (branch)The heavy guest particles embedded to superfluid helium can cause its $solidification^{1}$. The so-called Impurity Helium Solid Phase (IHSP) being stable then up T = 7K shows the regular arrangement of the impurities with their reliable isolation by helium atoms. The feasibility of previously excited species capture to IHSP may be achieved. So metastable N($^{2}$D) atoms display extremely long-lived, more than $10^{4}$ s, luminescence. Their radiative decay turns out to be caused solely by excimer-like state formation with accidentally neighbouring heavy $particle^{2}$. That was proved for N($^{2}$D)-Rg pairs (Rg = Ne, Ar, Kr, Xe) by both spectra shapes and emission lifetimes observed. For N($^{2}$D)-$N_{2}$ state the comparison of atomic $N(^{2}D-^{4}S)$ and rovibronic $N(^{2}D)-N_{2}(\nu = 0) \rightarrow N(^{4}S)-N_{2}(\nu = 1)$ spectra evidences their excimer nature as $well^{3}$. The distances between neighbour N atoms in IHSP, 1 mm, are small enough for cooperative bulk magnetic effects appearances. ESR experiments with N($^{4}$S) atoms show the effects of either magnetic alignment or spin-exchange narrowing

THERMOLUMINESCENCE OF IMPURITY-HELIUM SOLIDS IMMERSED IN LIQUID HELIUM

Acknowledgement: The work was carried out with support from Russian Foundation for Basic Research (Grant 99-03-33261). $^{a}$E.B. Gordon V. V. Khmelenko, A. A. Pelmenev, E.A. Popov, O.F. Pugachev, A.F. Shestakov, Chem. Phys. 170, 411(1993). $^{b}$R.E. Boltnev, E.B. Gordon, V.V. Khmelenko, I.N. Krushinskaya, M.V. Martyneko, A.A.Pelmenev, E.A. Popov, A.F. Shestakov, Chem. Phy., 189,367 (1994)Author Institution: Institute of Energy Problems of Chemical Physics; Institute of Problems of Chemical PhysicsA solidification of liquid helium around impurity particles injected in its volume results in IHSP (impurity-Helium Solid Phase) $formation ^{a}$, so the particles can be stabilized with inert environment during long time. Particular interest is stabilization of metastable particles. The capture of $N(^{2}D)$ atoms from discharge allows to save ones at T = 1.5 K during $10^{4}$ s -time comparable with their lifetime, $4.4 \times 10^{4}$ s. Nevertheless, even small temperature increase ($< 0.1$ K) causes the luminescence on the $^{2}D- ^{4}S$ transition. It was explained as thermoactivated association of neighbouring centers of IHSP. $N+N_{2}$ or $N + R_{g}$, which partially removes the prohibition because of ``heavy particle $effect""^{b}$. The main part of stabilized nitrogen atoms is in the ground state $^{4}S$, so thermoactivated mobility leads to the pair recombination N + N or $N+O(O_{2}$ presents as trace in condensed gas mixture). The results presented in report confirm that heating of IHSP sample causes a blue emission which can be assigned to excited states of $N_{2}$ or NO

Optical spectroscopy and current detection during warm-up and destruction of impurity–helium condensates

New experimental results on detection of optical spectra and ion currents during destruction of impurity–helium condensates (IHCs) have been obtained. It is shown that emission during IHC sample destruction is accompanied by current pulses, pressure peaks and temperature changes. The molecular bands of excimer molecules XeO* are assigned to molecules stabilized in films of molecular nitrogen covering the heavier cores of impurity clusters which form impurity–helium condensates

INFLUENCE OF SUB-MAXIMAL PHYSICAL LOAD ON BLOOD CELL PARAMETERS IN ATHLETES

Abstract. Blood cell reactions to a submaximal physical load were studied in nine male athletes aged from 18 to 22 years, involved in wrestling sports. Subpopulational profiling of blood cell was performed 7, 35, and 60 min after completing the physical exercises. An absolute increase in total nucleated cells, erythrocytes, neutrophils, monocytes, and T-lymphocytes was noted in blood counts at the 7-min time-point. Both absolute and relative increases were revealed for СD16+ and СD56+ natural killer cells, CD19+ B-cells, as well as for stem-like cell population (CD34+CD133+) at this period. It is worth of mention that all the tested blood parameters returned to basal ranges within 35 min after the physical exercise was completed. We suggest that the changes in blood cell parameters observed during first minutes after the physical load may characterize a physical potential of athletes. Thus, evaluation of these indices may be used for optimizing their training efforts

Oxygen atoms and nitrogen molecules as spectroscopic probes for the temperature determination in non-equilibrium cryogenic helium plasma jets

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