Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review Letters

Condensation of He Gas on Optically Excited Ag Atoms Below the Critical Temperature ( T<5.2K )

Zygmunt J. Jakubek, Qin Hui, Michio Takami

Published Jul 28, 1997• 30 citations
Publisher

Abstract

Laser induced fluorescence spectra of Ag atoms and their time profiles have been studied in cold He gas at temperatures 4.3--25 K and pressure $\ensuremath{\lesssim}1\mathrm{atm}$. The emission spectra following the excitation of the atomic $D2$ line consist of three narrow lines and three broadbands, which are assigned to transitions of Ag atoms and AgHe and ${\mathrm{AgHe}}_{2}$ exciplexes. Surprisingly long ( $\ensuremath{\gtrsim}300\mathrm{ns}$) effective emission lifetimes are observed at $T>{T}_{c}$ (5.2 K). The long lifetimes are the result of population trapping in the ${}^{2}{D}_{5/2}$ metastable state. At $T\ensuremath{\lesssim}{T}_{c}$, the effective lifetimes decrease to $\ensuremath{\lesssim}20\mathrm{ns}$ due to the condensation of He gas on the Ag atom in its ${}^{2}{D}_{5/2}$ state.

DOI
10.1103/physrevlett.79.629

Related papers

Optical spectra of atoms in liquid helium and cold helium gas

Michio Takami

Lineshapes associated with the absorption and emission spectra of neutral atoms in liquid helium and cold helium gas are discussed. A neutral atom in liquid helium forms a microcavity due to a strong short-range repulsive force between the helium and impurity atoms, producing very broad and largely blueshifted absorption bands and relatively narrow emission lines with much smaller shifts. A broad and weak emission band observed by exciting the D2 line of Ag atoms in liquid helium has confirmed the hypothesis that quenching of D2 emission lines for heavy group 1a and 1b atoms are due to the formation of exciplex. In cold helium gas, sudden decrease of the emission lifetimes below 5.2 K by the excitation of the D2 line of Ag atoms is attributed to the condensation of He atoms on the metastable 2D5/2 state. Very narrow absorption lines of Eu innershell electron transitions have revealed that superfluid helium behaves as a static and highly homogeneous low temperature matrix.

International Conference on Spectral Line Shapes (ICSLS)•Jan 1, 1999•0 citations

Laser-induced fluorescence spectra of Ba+*-He exciplexes produced in cold He gas

Yoshimitsu Fukuyama, Yoshiki Moriwaki, Yukari Matsuo

We report the observation of laser-induced fluorescence spectra of ${\text{Ba}}^{+*}\text{\ensuremath{-}}\text{He}$ exciplexes. The experiment is carried out in an environment of cold gaseous helium at a temperature range of $3--30\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. We have observed the emission spectra of exciplexes by means of excitation of the $6p\phantom{\rule{0.3em}{0ex}}^{2}P_{3∕2}\ensuremath{\leftarrow}6s\phantom{\rule{0.3em}{0ex}}^{2}S_{1∕2}$ transition of ${\text{Ba}}^{+}$ ions. It is found that these spectra are redshifted from the $D2$ emission line in the free space and are composed of several peaks. The experimental results are reproduced well by theoretical calculation of the emission spectra for vibrational levels of ${\text{Ba}}^{+*}\text{\ensuremath{-}}\text{He}$. We also investigate the vibrational dynamics of the $6p\phantom{\rule{0.3em}{0ex}}^{2}\ensuremath{\Pi}_{3∕2}$ state of ${\text{Ba}}^{+*}\text{\ensuremath{-}}\text{He}$, and we have determined the collision-induced vibrational relaxation cross sections of the $6p\phantom{\rule{0.3em}{0ex}}^{2}\ensuremath{\Pi}_{3∕2}$ state to be $9.7\ifmmode\pm\else\textpm\fi{}1.1\phantom{\rule{0.3em}{0ex}}{\mathrm{\AA{}}}^{2}$ at $15\phantom{\rule{0.3em}{0ex}}\mathrm{K}$.

Physical Review A•Apr 7, 2004•15 citations

Emission spectra of Rb*Hen exciplexes in a cold 4He gas

Keiichi Hirano, Katsunari Enomoto, M. Kumakura +2 more

We report on the systematic observation of emission spectra of ${\mathrm{Rb}}^{*}{\mathrm{He}}_{n}$ exciplexes $(n=1,2,\dots{},6),$ realized by exciting Rb atoms to the ${5}^{2}P$ states $({\mathrm{Rb}}^{*})$ in a cold ${}^{4}\mathrm{He}$ gas. The observed broad spectral components are assigned to ${\mathrm{Rb}}^{*}{\mathrm{He}}_{n}$ $(n=1--6)$ using theoretical spectra obtained from ab initio potential curves. The dynamics of the exciplex formation is discussed, based on the observed temperature dependence of the spectra. The He gas density dependence of the spectra of ${\mathrm{Rb}}^{*}\mathrm{He}$ is understood as a change in the population distribution over the vibrational levels. The present results are compared with our previous work with Cs [K. Enomoto et al., Phys. Rev. A 66, 042505 (2002)], and differences are explained in terms of the difference in the fine-structure splitting. Furthermore, we show the emission spectrum observed after the excitation of Rb in liquid He and conclude that it is the fluorescence from the exciplex ${\mathrm{Rb}}^{*}{\mathrm{He}}_{6}.$

Physical Review A•Jul 25, 2003•39 citations

Emission spectra of (RbHen)-He-* exciplexes in a cold He-4 gas

Keiichi Hirano, Katsunari Enomoto, M. Kumakura +2 more

We report on the systematic observation of emission spectra of ${\mathrm{Rb}}^{*}{\mathrm{He}}_{n}$ exciplexes $(n=1,2,\dots{},6),$ realized by exciting Rb atoms to the ${5}^{2}P$ states $({\mathrm{Rb}}^{*})$ in a cold ${}^{4}\mathrm{He}$ gas. The observed broad spectral components are assigned to ${\mathrm{Rb}}^{*}{\mathrm{He}}_{n}$ $(n=1--6)$ using theoretical spectra obtained from ab initio potential curves. The dynamics of the exciplex formation is discussed, based on the observed temperature dependence of the spectra. The He gas density dependence of the spectra of ${\mathrm{Rb}}^{*}\mathrm{He}$ is understood as a change in the population distribution over the vibrational levels. The present results are compared with our previous work with Cs [K. Enomoto et al., Phys. Rev. A 66, 042505 (2002)], and differences are explained in terms of the difference in the fine-structure splitting. Furthermore, we show the emission spectrum observed after the excitation of Rb in liquid He and conclude that it is the fluorescence from the exciplex ${\mathrm{Rb}}^{*}{\mathrm{He}}_{6}.$

Physical Review A•Jul 1, 2003•0 citations

Laser spectroscopy of thulium atoms implanted in liquid and solid 4 He

Kiyoshi Ishikawa, A. Hatakeyama, Koichi Gosyono-o +3 more

The excitation, emission spectra, and decay curves of the emission intensity of thulium atoms implanted in liquid and solid helium were observed in the presence and absence of an external magnetic field. The observed narrow line (width $\ensuremath{\sim}0.1$ nm) of the excitation spectrum at 590.60 nm is assigned as a zero-phonon transition from the electronic ground state ${4f}^{13}{(}^{2}{F}_{7/2}^{o}{)6s}^{2}$, which indicates that the transition between the inner shells is weakly perturbed by surrounding helium atoms. The pressure dependence of the emission wavelength suggests that the symmetry of helium atoms distributed around a thulium atom in the solid phase is similar to that in the liquid phase. The emission intensity was stable and large in the solid phase since thulium atoms were trapped at a density of 10${}^{10}$--10${}^{11}$ atoms/cm${}^{3}$. The lifetime of the excited state was measured to be $7.09\ifmmode\pm\else\textpm\fi{}0.04$ $\ensuremath{\mu}$s, which was longer than that of the ${4f}^{12}{(}^{3}{H}_{6}{)5d}_{5/2}{6s}^{2}$ ${(6,5/2)}_{7/2}$ state of free thulium atoms. The excited state is expected to be a mixed state of the ${4f}^{12}{5d6s}^{2}$ and ${4f}^{13}6s6p$ configurations. The metastable state ${4f}^{13}{(}^{2}{F}_{5/2}^{o}{)6s}^{2}$ is populated by a radiative transition from this excited state and relaxes to the ground state through a magnetic dipole transition. The lifetime of the metastable state of a neutral thulium atom was measured to be $75\ifmmode\pm\else\textpm\fi{}3$ ms.

Physical review. B, Condensed matter•Jul 1, 1997•36 citations

Spectroscopy of barium atoms in liquid and solid helium matrices

Victor Lebedev, Peter Moroshkin, Antoine Weis

We present an exhaustive overview of optical absorption and laser-induced fluorescence lines of Ba atoms in liquid and solid helium matrices in visible and near-infrared spectral ranges. Due to the increased density of isolated atoms, we have found a large number of spectral lines that were not observed in condensed helium matrices before. We have also measured the lifetimes of metastable states. The lowest ${}^{3}{D}_{1}$ metastable state has lifetime of 2.6 s and can be used as an intermediate state in two-step excitations of high-lying states. Various matrix-induced radiationless population transfer channels have been identified.

Physical Review A•Aug 3, 2011•14 citations
Laser induced fluorescence spectra of Ag atoms and their time profiles have been studied in cold He gas at temperatures 4.3--25 K and pressure \ensuremath≲1atm\ensuremath{\lesssim}1\mathrm{atm}\ensuremath≲1atm. The emission spectra following the excitation of the atomic D2D2D2 line consist of three narrow lines and three broadbands, which are assigned to transitions of Ag atoms and AgHe and AgHe2{\mathrm{AgHe}}_{2}AgHe2​ exciplexes. Surprisingly long ( \ensuremath≳300ns\ensuremath{\gtrsim}300\mathrm{ns}\ensuremath≳300ns) effective emission lifetimes are observed at T>TcT>{T}_{c}T>Tc​ (5.2 K). The long lifetimes are the result of population trapping in the 2D5/2{}^{2}{D}_{5/2}2D5/2​ metastable state. At T\ensuremath≲TcT\ensuremath{\lesssim}{T}_{c}T\ensuremath≲Tc​, the effective lifetimes decrease to \ensuremath≲20ns\ensuremath{\lesssim}20\mathrm{ns}\ensuremath≲20ns due to the condensation of He gas on the Ag atom in its 2D5/2{}^{2}{D}_{5/2}2D5/2​ state.
Lineshapes associated with the absorption and emission spectra of neutral atoms in liquid helium and cold helium gas are discussed. A neutral atom in liquid helium forms a microcavity due to a strong short-range repulsive force between the helium and impurity atoms, producing very broad and largely blueshifted absorption bands and relatively narrow emission lines with much smaller shifts. A broad and weak emission band observed by exciting the D2 line of Ag atoms in liquid helium has confirmed the hypothesis that quenching of D2 emission lines for heavy group 1a and 1b atoms are due to the formation of exciplex. In cold helium gas, sudden decrease of the emission lifetimes below 5.2 K by the excitation of the D2 line of Ag atoms is attributed to the condensation of He atoms on the metastable 2D5/2 state. Very narrow absorption lines of Eu innershell electron transitions have revealed that superfluid helium behaves as a static and highly homogeneous low temperature matrix.
We report the observation of laser-induced fluorescence spectra of ${\text{Ba}}^{+*}\text{\ensuremath{-}}\text{He}$ exciplexes. The experiment is carried out in an environment of cold gaseous helium at a temperature range of 3−−30K3--30\phantom{\rule{0.3em}{0ex}}\mathrm{K}3−−30K. We have observed the emission spectra of exciplexes by means of excitation of the $6p\phantom{\rule{0.3em}{0ex}}^{2}P_{3∕2}\ensuremath{\leftarrow}6s\phantom{\rule{0.3em}{0ex}}^{2}S_{1∕2}$ transition of Ba+{\text{Ba}}^{+}Ba+ ions. It is found that these spectra are redshifted from the D2D2D2 emission line in the free space and are composed of several peaks. The experimental results are reproduced well by theoretical calculation of the emission spectra for vibrational levels of ${\text{Ba}}^{+*}\text{\ensuremath{-}}\text{He}$. We also investigate the vibrational dynamics of the $6p\phantom{\rule{0.3em}{0ex}}^{2}\ensuremath{\Pi}_{3∕2}$ state of ${\text{Ba}}^{+*}\text{\ensuremath{-}}\text{He}$, and we have determined the collision-induced vibrational relaxation cross sections of the $6p\phantom{\rule{0.3em}{0ex}}^{2}\ensuremath{\Pi}_{3∕2}$ state to be $9.7\ifmmode\pm\else\textpm\fi{}1.1\phantom{\rule{0.3em}{0ex}}{\mathrm{\AA{}}}^{2}$ at 15K15\phantom{\rule{0.3em}{0ex}}\mathrm{K}15K.
We report on the systematic observation of emission spectra of Rb∗Hen{\mathrm{Rb}}^{*}{\mathrm{He}}_{n}Rb∗Hen​ exciplexes (n=1,2,…,6),(n=1,2,\dots{},6),(n=1,2,…,6), realized by exciting Rb atoms to the 52P{5}^{2}P52P states (Rb∗)({\mathrm{Rb}}^{*})(Rb∗) in a cold 4He{}^{4}\mathrm{He}4He gas. The observed broad spectral components are assigned to Rb∗Hen{\mathrm{Rb}}^{*}{\mathrm{He}}_{n}Rb∗Hen​ (n=1−−6)(n=1--6)(n=1−−6) using theoretical spectra obtained from ab initio potential curves. The dynamics of the exciplex formation is discussed, based on the observed temperature dependence of the spectra. The He gas density dependence of the spectra of Rb∗He{\mathrm{Rb}}^{*}\mathrm{He}Rb∗He is understood as a change in the population distribution over the vibrational levels. The present results are compared with our previous work with Cs [K. Enomoto et al., Phys. Rev. A 66, 042505 (2002)], and differences are explained in terms of the difference in the fine-structure splitting. Furthermore, we show the emission spectrum observed after the excitation of Rb in liquid He and conclude that it is the fluorescence from the exciplex Rb∗He6.{\mathrm{Rb}}^{*}{\mathrm{He}}_{6}.Rb∗He6​.
We report on the systematic observation of emission spectra of Rb∗Hen{\mathrm{Rb}}^{*}{\mathrm{He}}_{n}Rb∗Hen​ exciplexes (n=1,2,…,6),(n=1,2,\dots{},6),(n=1,2,…,6), realized by exciting Rb atoms to the 52P{5}^{2}P52P states (Rb∗)({\mathrm{Rb}}^{*})(Rb∗) in a cold 4He{}^{4}\mathrm{He}4He gas. The observed broad spectral components are assigned to Rb∗Hen{\mathrm{Rb}}^{*}{\mathrm{He}}_{n}Rb∗Hen​ (n=1−−6)(n=1--6)(n=1−−6) using theoretical spectra obtained from ab initio potential curves. The dynamics of the exciplex formation is discussed, based on the observed temperature dependence of the spectra. The He gas density dependence of the spectra of Rb∗He{\mathrm{Rb}}^{*}\mathrm{He}Rb∗He is understood as a change in the population distribution over the vibrational levels. The present results are compared with our previous work with Cs [K. Enomoto et al., Phys. Rev. A 66, 042505 (2002)], and differences are explained in terms of the difference in the fine-structure splitting. Furthermore, we show the emission spectrum observed after the excitation of Rb in liquid He and conclude that it is the fluorescence from the exciplex Rb∗He6.{\mathrm{Rb}}^{*}{\mathrm{He}}_{6}.Rb∗He6​.
The excitation, emission spectra, and decay curves of the emission intensity of thulium atoms implanted in liquid and solid helium were observed in the presence and absence of an external magnetic field. The observed narrow line (width $\ensuremath{\sim}0.1$ nm) of the excitation spectrum at 590.60 nm is assigned as a zero-phonon transition from the electronic ground state 4f13(2F7/2o)6s2{4f}^{13}{(}^{2}{F}_{7/2}^{o}{)6s}^{2}4f13(2F7/2o​)6s2, which indicates that the transition between the inner shells is weakly perturbed by surrounding helium atoms. The pressure dependence of the emission wavelength suggests that the symmetry of helium atoms distributed around a thulium atom in the solid phase is similar to that in the liquid phase. The emission intensity was stable and large in the solid phase since thulium atoms were trapped at a density of 1010{}^{10}10--1011{}^{11}11 atoms/cm3{}^{3}3. The lifetime of the excited state was measured to be $7.09\ifmmode\pm\else\textpm\fi{}0.04$ $\ensuremath{\mu}$s, which was longer than that of the 4f12(3H6)5d5/26s2{4f}^{12}{(}^{3}{H}_{6}{)5d}_{5/2}{6s}^{2}4f12(3H6​)5d5/2​6s2 (6,5/2)7/2{(6,5/2)}_{7/2}(6,5/2)7/2​ state of free thulium atoms. The excited state is expected to be a mixed state of the 4f125d6s2{4f}^{12}{5d6s}^{2}4f125d6s2 and 4f136s6p{4f}^{13}6s6p4f136s6p configurations. The metastable state 4f13(2F5/2o)6s2{4f}^{13}{(}^{2}{F}_{5/2}^{o}{)6s}^{2}4f13(2F5/2o​)6s2 is populated by a radiative transition from this excited state and relaxes to the ground state through a magnetic dipole transition. The lifetime of the metastable state of a neutral thulium atom was measured to be $75\ifmmode\pm\else\textpm\fi{}3$ ms.
We present an exhaustive overview of optical absorption and laser-induced fluorescence lines of Ba atoms in liquid and solid helium matrices in visible and near-infrared spectral ranges. Due to the increased density of isolated atoms, we have found a large number of spectral lines that were not observed in condensed helium matrices before. We have also measured the lifetimes of metastable states. The lowest 3D1{}^{3}{D}_{1}3D1​ metastable state has lifetime of 2.6 s and can be used as an intermediate state in two-step excitations of high-lying states. Various matrix-induced radiationless population transfer channels have been identified.