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

AIAA AVIATION Forum

Kinetic Modeling of Optically Pumped Barium Vapor and Impacts of Buffer Gas on 355 nm Absorption Lineshape

Madison E. Hetlage, Christopher Limbach

Published Jul 28, 2021• 1 citation
Publisher

Abstract

View Video Presentation: https://doi.org/10.2514/6.2021-3107.vid This work is a portion of a combined theoretical and experimental effort to develop a controllable excited state barium vapor source to be used as a notch filter. The energy pooling properties of the low-lying levels of barium, which make it ideal for this application, have been the subject of several past kinetics studies. This work was utilized to develop a 6-level kinetics model, incorporating collisional and radiative decay and, most critically, diffusional quenching. This model demonstrates efficient pumping of the metastable manifold in the 6s5d 3DJ levels, particularly the 6s5d 3D2 level which will be utilized by the proposed filter. A vacuum vapor cell and its implementation into a counter-propagating, optically pumped absorption spectroscopy arrangement are also described. Measurements of the optically pumping transition (6s2 1S0-- 6s6p 3P01, 791 nm) and the proposed filtering transition (6s5d 3D2 -- 6s5f 3F02, 355 nm) have been performed with this system. To our knowledge, these are the first measurements of this 355 nm filtering transition. These measurements demonstrate a non-Maxwellian lineshape, suggesting a non-thermalized metastable 6s5d 3D2 level. The measured ground state depletion and 3D2 population agree with the model trends but show quantitative discrepancies which require further study. A detailed theoretical analysis of the effects on filter performance of incorporating an argon buffer gas into the vapor source is also presented. This work shows promise for creating a narrowband absorption feature with increased optical depth.

DOI
10.2514/6.2021-3107

Related papers

Experimental and analytical evaluation of an active barium vapor notch filter functioning at 355 nm

Madison E. Hetlage, Christopher Limbach

This work presents an experimental and theoretical study of the 6s21S0→6s6p3P10 (791 nm) and 5s5d3D2→6s5f3F20 (355 nm) transitions within a low vapor pressure barium vapor in the absence of a buffer gas. To the authors’ knowledge, this is the first measurement of the latter absorption feature. The study is motivated by the development of an optically controlled atomic vapor notch filter functioning at the third harmonic of the commonly used Nd:YAG laser at 355 nm. The low-pressure environment within the vapor source has enabled a deeper understanding of barium vapor collisional and velocity changing properties with a simple pump-probe spectroscopy measurement. The results demonstrate depletion of the ground state and subsequent population of the 5s5d3D2 level. Most notably, the 5s5d3D2→6s5f3F20 transition displays a non-thermal, cusped absorption curve. An analysis of this line shape in the context of existing analytical collisional kernels is presented. Additionally, a six-level kinetic model of the low-lying energy levels, incorporating spatial diffusion and collisional and radiative transitions, is introduced and compared to the measured level populations for the barium ground state and excited 5s5d3D2 state.

Applied Optics•May 5, 2022•3 citations

Excitation transfer among, and quenching of, the barium 6s5d 3 DJ metastable levels due to collisions with argon, nitrogen, and barium perturbers

E. Ehrlacher, John Huennekens

We describe a set of experiments that investigate excitation transfer among the barium 6s5d $^{3}$${\mathit{D}}_{\mathit{J}}$ metastable levels due to collisions with argon perturber atoms, and quenching of atoms in these levels by nitrogen perturber molecules. The metastable levels were populated through optical pumping of the 6${\mathit{s}}^{2}$ $^{1}$${\mathit{S}}_{0}$\ensuremath{\rightarrow}6s6p $^{3}$${\mathit{P}}_{1}^{\mathit{o}}$ intercombination transition with a pulsed laser, followed by stimulated emission or stimulated Raman scattering into the 6s5d $^{3}$${\mathit{D}}_{1,2}$ levels. Collisional mixing then distributed population throughout the $^{3}$${\mathit{D}}_{\mathit{J}}$ levels. Time-dependent absorption coefficients were obtained by measuring the transmission of a weak cw probe laser beam (after the pulsed laser fired) at several perturber number densities. Argon buffer gas was used to investigate fine-structure mixing, and nitrogen was used to study quenching. The time-dependent absorption coefficients were fitted to appropriate fitting functions, obtained by solving the set of coupled rate equations used to model the time evolution of the metastable level populations. The buildup rates of the initially unpopulated $^{3}$${\mathit{D}}_{3}$ and underpopulated $^{3}$${\mathit{D}}_{1}$ levels were used to determine the collisional mixing rates, while the measured decay rates of the $^{3}$${\mathit{D}}_{\mathit{J}}$ level populations yielded the quenching rates. From plots of buildup rates versus argon number density for the $^{3}$${\mathit{D}}_{1,3}$ states, we were able to determine four of the six fine-structure mixing rate coefficients ${\mathit{k}}_{\mathit{i}\mathit{j}}$.The results are ${\mathit{k}}_{12}$=(1.71\ifmmode\pm\else\textpm\fi{}0.18), ${\mathit{k}}_{21}$=(1.39\ifmmode\pm\else\textpm\fi{}0.13), ${\mathit{k}}_{23}$=(1.42\ifmmode\pm\else\textpm\fi{}0.13), and ${\mathit{k}}_{32}$=(1.92\ifmmode\pm\else\textpm\fi{}0.16)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}13}$ ${\mathrm{cm}}^{3}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$. The experiment is not sensitive to the values of ${\mathit{k}}_{13}$ and ${\mathit{k}}_{31}$. Estimated rate coefficients for excitation transfer among the $^{3}$${\mathit{D}}_{\mathit{J}}$ levels due to collisions with barium atoms are ${\mathit{k}}_{21}^{\mathrm{Ba}}$=1.3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$ ${\mathrm{cm}}^{3}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$ and ${\mathit{k}}_{23}^{\mathrm{Ba}}$=5.8\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$ ${\mathrm{cm}}^{3}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$. A plot of the population decay rates versus ${\mathrm{N}}_{2}$ number density for each of the three metastable levels yielded the average nitrogen quenching rate coefficient ${\mathit{k}}_{\mathit{q}}$=(3.14\ifmmode\pm\else\textpm\fi{}0.19)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}11}$ ${\mathrm{cm}}^{3}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$.

Physical Review A•Dec 1, 1994•26 citations

Diffusion of barium atoms in the 6s5d 3 DJ metastable levels and the 6 s2 1 S0 ground state through noble-gas perturbers

R. K. Namiotka, E. Ehrlacher, J. Sagle +5 more

We describe a set of experiments that investigate diffusion of barium 6s5d${\mathrm{}}^{3}$${\mathit{D}}_{\mathit{J}}$ metastable level and 6${\mathit{s}}^{2}$${\mathrm{}}^{1}$${\mathit{S}}_{0}$ ground-state atoms through the noble gases: He, Ne, Ar, Kr, and Xe. The barium metastable levels were populated through optical pumping of the 6${\mathit{s}}^{2}$${\mathrm{}}^{1}$${\mathit{S}}_{0}$\ensuremath{\rightarrow}6s6p${\mathrm{}}^{3}$${\mathit{P}}_{1}^{\mathit{o}}$ intercombination transition with a pulsed laser, followed by spontaneous or stimulated emission into the 6s5d${\mathrm{}}^{3}$${\mathit{D}}_{1,2}$ levels. Collisional mixing then distributed population throughout the 6s5d${\mathrm{}}^{3}$${\mathit{D}}_{\mathit{J}}$ levels. A weak narrow-band cw laser was tuned to appropriate transitions to probe the spatial distribution of metastable level atoms, as well as the hole created in the ground-state spatial distribution, by the pulsed laser. Time-dependent absorption coefficients were obtained by measuring the transmission of the probe laser at several different pump-probe spatial separations. From these absorption data, spatial number density profiles were mapped out for various times following the firing of the pump laser. These density profiles were used to determine the diffusion coefficient for each state at a particular buffer-gas pressure and temperature. From these pressure- and temperature-dependent diffusion coefficients D, we determined the thermally averaged diffusion cross sections ${\mathrm{\ensuremath{\sigma}}}_{\mathit{D}}$(6s5d${\mathrm{}}^{3}$${\mathit{D}}_{\mathit{J}}$) and ${\mathrm{\ensuremath{\sigma}}}_{\mathit{D}}$(6${\mathit{s}}^{2}$${\mathrm{}}^{1}$${\mathit{S}}_{0}$) for the metastable and ground-state atoms diffusing through the noble gases, respectively. We also report values for the scaled standard diffusion coefficients ${\mathit{D}}_{0}$. Our experimental values of the thermally averaged diffusion cross sections ${\mathrm{\ensuremath{\sigma}}}_{\mathit{D}}$(6s5d${\mathrm{}}^{3}$${\mathit{D}}_{\mathit{J}}$) and ${\mathrm{\ensuremath{\sigma}}}_{\mathit{D}}$(6${\mathit{s}}^{2}$${\mathrm{}}^{1}$${\mathit{S}}_{0}$) for the barium-helium system are compared with values calculated from published, theoretical barium-helium potentials and the agreement is excellent. \textcopyright{} 1996 The American Physical Society.

Physical Review A•Jul 1, 1996•16 citations

Energy-pooling collisions in barium

Jonathan Andrew Neuman, Alan C. Gallagher, J. Cooper

Rate coefficients for energy-pooling collisions between low-lying excited states of Ba have been measured. The 6s6p${(}^{3}$${\mathit{P}}_{1}$) level in Ba is pumped by a cw diode laser, and radiative decay and collisions with buffer-gas atoms also populate the 5d6s${(}^{1}$D) and 5d6s${(}^{3}$D) metastable levels. The densities of these low-lying excited states are measured by the absorption of lines from a Ba hollow-cathode lamp, and the states populated by energy-pooling collisions are studied by comparing their fluorescence intensity to that of the laser-excited level. The rate coefficients are on the order of gas-kinetic rates, and they are not strongly dependent on energy defect, spin changes, or angular-momentum changes.

Physical Review A•Aug 1, 1994•20 citations

Pair-absorption-pumped barium laser

R. W. Falcone, G. Zdasiuk

This is the first reported demonstration of the use of pair-absorption transitions for optically pumping lasers. In a mixture of barium and thallium metal vapors, single-photon absorption of 3867-A laser light caused simultaneous excitation of colliding ground-state atoms to the Ba(6s6p 1P1(o)) and Tl(6p 2P(3/2)(o)) excited states. Excited-state densities of about 10(14) cm(-3) were created, and subsequent laser emission on the Ba(6s6p 1PI(o)) - Ba(6s5d 1D2) atomic transition at 1.5 microm was observed.

Optics Letters•Apr 1, 1980•9 citations

Energy pooling in barium with state excitation

G. De Filippo, Sb R, Slobodan Milošević +1 more

Energy-pooling collisions between low-lying excited states of Ba have been studied. We have used a CW dye laser to excite the level in Ba. Radiative decay and collisions with Ba or buffer-gas atoms (Ar, He) populate also the , and metastable levels. The spatial density distributions of these excited levels were measured by the absorption of lines from a Ba hollow-cathode lamp as a function of laser frequency. When the laser was on the exact atomic resonance we observed fluorescence from the , , , , , , and states populated by energy-pooling collisions of Ba( , ). By changing the buffer gas pressure the fluorescence intensity ratio between - and - transitions changes dramatically. This is found to be due to redistribution of population among metastable levels, both in magnitude and space. In addition, we have found that the and metastable levels are also populated when the laser is tuned to the blue from the 553.5 nm line under which conditions a pronounced red-shifted light cone (cone emission) is observed.

Journal of Physics B Atomic Molecular and Optical Physics•May 28, 1996•8 citations
View Video Presentation: https://doi.org/10.2514/6.2021-3107.vid This work is a portion of a combined theoretical and experimental effort to develop a controllable excited state barium vapor source to be used as a notch filter. The energy pooling properties of the low-lying levels of barium, which make it ideal for this application, have been the subject of several past kinetics studies. This work was utilized to develop a 6-level kinetics model, incorporating collisional and radiative decay and, most critically, diffusional quenching. This model demonstrates efficient pumping of the metastable manifold in the 6s5d 3DJ levels, particularly the 6s5d 3D2 level which will be utilized by the proposed filter. A vacuum vapor cell and its implementation into a counter-propagating, optically pumped absorption spectroscopy arrangement are also described. Measurements of the optically pumping transition (6s2 1S0-- 6s6p 3P01, 791 nm) and the proposed filtering transition (6s5d 3D2 -- 6s5f 3F02, 355 nm) have been performed with this system. To our knowledge, these are the first measurements of this 355 nm filtering transition. These measurements demonstrate a non-Maxwellian lineshape, suggesting a non-thermalized metastable 6s5d 3D2 level. The measured ground state depletion and 3D2 population agree with the model trends but show quantitative discrepancies which require further study. A detailed theoretical analysis of the effects on filter performance of incorporating an argon buffer gas into the vapor source is also presented. This work shows promise for creating a narrowband absorption feature with increased optical depth.
This work presents an experimental and theoretical study of the 6s21S0→6s6p3P10 (791 nm) and 5s5d3D2→6s5f3F20 (355 nm) transitions within a low vapor pressure barium vapor in the absence of a buffer gas. To the authors’ knowledge, this is the first measurement of the latter absorption feature. The study is motivated by the development of an optically controlled atomic vapor notch filter functioning at the third harmonic of the commonly used Nd:YAG laser at 355 nm. The low-pressure environment within the vapor source has enabled a deeper understanding of barium vapor collisional and velocity changing properties with a simple pump-probe spectroscopy measurement. The results demonstrate depletion of the ground state and subsequent population of the 5s5d3D2 level. Most notably, the 5s5d3D2→6s5f3F20 transition displays a non-thermal, cusped absorption curve. An analysis of this line shape in the context of existing analytical collisional kernels is presented. Additionally, a six-level kinetic model of the low-lying energy levels, incorporating spatial diffusion and collisional and radiative transitions, is introduced and compared to the measured level populations for the barium ground state and excited 5s5d3D2 state.
We describe a set of experiments that investigate excitation transfer among the barium 6s5d 3^{3}3DJ{\mathit{D}}_{\mathit{J}}DJ​ metastable levels due to collisions with argon perturber atoms, and quenching of atoms in these levels by nitrogen perturber molecules. The metastable levels were populated through optical pumping of the 6s2{\mathit{s}}^{2}s2 1^{1}1S0{\mathit{S}}_{0}S0​\ensuremath{\rightarrow}6s6p 3^{3}3P1o{\mathit{P}}_{1}^{\mathit{o}}P1o​ intercombination transition with a pulsed laser, followed by stimulated emission or stimulated Raman scattering into the 6s5d 3^{3}3D1,2{\mathit{D}}_{1,2}D1,2​ levels. Collisional mixing then distributed population throughout the 3^{3}3DJ{\mathit{D}}_{\mathit{J}}DJ​ levels. Time-dependent absorption coefficients were obtained by measuring the transmission of a weak cw probe laser beam (after the pulsed laser fired) at several perturber number densities. Argon buffer gas was used to investigate fine-structure mixing, and nitrogen was used to study quenching. The time-dependent absorption coefficients were fitted to appropriate fitting functions, obtained by solving the set of coupled rate equations used to model the time evolution of the metastable level populations. The buildup rates of the initially unpopulated 3^{3}3D3{\mathit{D}}_{3}D3​ and underpopulated 3^{3}3D1{\mathit{D}}_{1}D1​ levels were used to determine the collisional mixing rates, while the measured decay rates of the 3^{3}3DJ{\mathit{D}}_{\mathit{J}}DJ​ level populations yielded the quenching rates. From plots of buildup rates versus argon number density for the 3^{3}3D1,3{\mathit{D}}_{1,3}D1,3​ states, we were able to determine four of the six fine-structure mixing rate coefficients kij{\mathit{k}}_{\mathit{i}\mathit{j}}kij​.The results are k12{\mathit{k}}_{12}k12​=(1.71\ifmmode\pm\else\textpm\fi{}0.18), k21{\mathit{k}}_{21}k21​=(1.39\ifmmode\pm\else\textpm\fi{}0.13), k23{\mathit{k}}_{23}k23​=(1.42\ifmmode\pm\else\textpm\fi{}0.13), and k32{\mathit{k}}_{32}k32​=(1.92\ifmmode\pm\else\textpm\fi{}0.16)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}13}$ cm3{\mathrm{cm}}^{3}cm3 ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$. The experiment is not sensitive to the values of k13{\mathit{k}}_{13}k13​ and k31{\mathit{k}}_{31}k31​. Estimated rate coefficients for excitation transfer among the 3^{3}3DJ{\mathit{D}}_{\mathit{J}}DJ​ levels due to collisions with barium atoms are k21Ba{\mathit{k}}_{21}^{\mathrm{Ba}}k21Ba​=1.3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$ cm3{\mathrm{cm}}^{3}cm3 ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$ and k23Ba{\mathit{k}}_{23}^{\mathrm{Ba}}k23Ba​=5.8\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$ cm3{\mathrm{cm}}^{3}cm3 ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$. A plot of the population decay rates versus N2{\mathrm{N}}_{2}N2​ number density for each of the three metastable levels yielded the average nitrogen quenching rate coefficient kq{\mathit{k}}_{\mathit{q}}kq​=(3.14\ifmmode\pm\else\textpm\fi{}0.19)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}11}$ cm3{\mathrm{cm}}^{3}cm3 ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$.
We describe a set of experiments that investigate diffusion of barium 6s5d3{\mathrm{}}^{3}3DJ{\mathit{D}}_{\mathit{J}}DJ​ metastable level and 6s2{\mathit{s}}^{2}s21{\mathrm{}}^{1}1S0{\mathit{S}}_{0}S0​ ground-state atoms through the noble gases: He, Ne, Ar, Kr, and Xe. The barium metastable levels were populated through optical pumping of the 6s2{\mathit{s}}^{2}s21{\mathrm{}}^{1}1S0{\mathit{S}}_{0}S0​\ensuremath{\rightarrow}6s6p3{\mathrm{}}^{3}3P1o{\mathit{P}}_{1}^{\mathit{o}}P1o​ intercombination transition with a pulsed laser, followed by spontaneous or stimulated emission into the 6s5d3{\mathrm{}}^{3}3D1,2{\mathit{D}}_{1,2}D1,2​ levels. Collisional mixing then distributed population throughout the 6s5d3{\mathrm{}}^{3}3DJ{\mathit{D}}_{\mathit{J}}DJ​ levels. A weak narrow-band cw laser was tuned to appropriate transitions to probe the spatial distribution of metastable level atoms, as well as the hole created in the ground-state spatial distribution, by the pulsed laser. Time-dependent absorption coefficients were obtained by measuring the transmission of the probe laser at several different pump-probe spatial separations. From these absorption data, spatial number density profiles were mapped out for various times following the firing of the pump laser. These density profiles were used to determine the diffusion coefficient for each state at a particular buffer-gas pressure and temperature. From these pressure- and temperature-dependent diffusion coefficients D, we determined the thermally averaged diffusion cross sections ${\mathrm{\ensuremath{\sigma}}}_{\mathit{D}}$(6s5d3{\mathrm{}}^{3}3DJ{\mathit{D}}_{\mathit{J}}DJ​) and ${\mathrm{\ensuremath{\sigma}}}_{\mathit{D}}$(6s2{\mathit{s}}^{2}s21{\mathrm{}}^{1}1S0{\mathit{S}}_{0}S0​) for the metastable and ground-state atoms diffusing through the noble gases, respectively. We also report values for the scaled standard diffusion coefficients D0{\mathit{D}}_{0}D0​. Our experimental values of the thermally averaged diffusion cross sections ${\mathrm{\ensuremath{\sigma}}}_{\mathit{D}}$(6s5d3{\mathrm{}}^{3}3DJ{\mathit{D}}_{\mathit{J}}DJ​) and ${\mathrm{\ensuremath{\sigma}}}_{\mathit{D}}$(6s2{\mathit{s}}^{2}s21{\mathrm{}}^{1}1S0{\mathit{S}}_{0}S0​) for the barium-helium system are compared with values calculated from published, theoretical barium-helium potentials and the agreement is excellent. \textcopyright{} 1996 The American Physical Society.
Rate coefficients for energy-pooling collisions between low-lying excited states of Ba have been measured. The 6s6p(3{(}^{3}(3P1{\mathit{P}}_{1}P1​) level in Ba is pumped by a cw diode laser, and radiative decay and collisions with buffer-gas atoms also populate the 5d6s(1{(}^{1}(1D) and 5d6s(3{(}^{3}(3D) metastable levels. The densities of these low-lying excited states are measured by the absorption of lines from a Ba hollow-cathode lamp, and the states populated by energy-pooling collisions are studied by comparing their fluorescence intensity to that of the laser-excited level. The rate coefficients are on the order of gas-kinetic rates, and they are not strongly dependent on energy defect, spin changes, or angular-momentum changes.
This is the first reported demonstration of the use of pair-absorption transitions for optically pumping lasers. In a mixture of barium and thallium metal vapors, single-photon absorption of 3867-A laser light caused simultaneous excitation of colliding ground-state atoms to the Ba(6s6p 1P1(o)) and Tl(6p 2P(3/2)(o)) excited states. Excited-state densities of about 10(14) cm(-3) were created, and subsequent laser emission on the Ba(6s6p 1PI(o)) - Ba(6s5d 1D2) atomic transition at 1.5 microm was observed.
Energy-pooling collisions between low-lying excited states of Ba have been studied. We have used a CW dye laser to excite the level in Ba. Radiative decay and collisions with Ba or buffer-gas atoms (Ar, He) populate also the , and metastable levels. The spatial density distributions of these excited levels were measured by the absorption of lines from a Ba hollow-cathode lamp as a function of laser frequency. When the laser was on the exact atomic resonance we observed fluorescence from the , , , , , , and states populated by energy-pooling collisions of Ba( , ). By changing the buffer gas pressure the fluorescence intensity ratio between - and - transitions changes dramatically. This is found to be due to redistribution of population among metastable levels, both in magnitude and space. In addition, we have found that the and metastable levels are also populated when the laser is tuned to the blue from the 553.5 nm line under which conditions a pronounced red-shifted light cone (cone emission) is observed.