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

Proceedings of the Physical Society

Inverted populations in thallium vapours

V. G. Velculescu

Published Feb 1, 1966• 0 citations
Publisher

Abstract

The possibility of obtaining population inversion between the 7 2 P 3/2 and 7 2 S 1/2 thallium levels is investigated, mercury being used as the pumping element. The inversion attained in a radio-frequency discharge at 39 Mc/s is estimated to be, under certain conditions, of the same order of magnitude as the laser threshold inversion.
DOI
10.1088/0370-1328/87/2/323

Related papers

Pulsed laser based on a resonance—metastable level transition in mercury ion

Svetlana V. Markova, Gueorgii G. Petrash

The method of doubled pulses was used to achieve pulsed lasing due to the 5 d 10 6 p 2 P 3/2 —5 d 9 6 s 2 2 D 5/2 transition in the mercury ion (λ = 398 nm), similar to efficient lasing transitions in copper and gold atoms. Discharge tubes with inner diameters 4 and 8 mm and 30 cm long were used. They were filled with neon or helium as the buffer gases. There was a significant difference between lasing in the narrow and wide tubes. In the wide tube it was possible to observe lasing only when the delay between the pulses was short; the beam was not ring-shaped, contrary to what was found earlier for the narrow tube. Lasing was observed even when the delay between the two pulses was less than 5 μs, but lasing disappeared when heating of the tube became stronger as the pulse repetition frequency was increased. Possible population and inversion mechanisms were analysed.

Quantum Electronics•Sep 30, 1995•2 citations

Coherently pumped two-frequency laser-type devices

I. R. Senitzky

A three-level system which radiates at both intermediate transition frequencies is considered to be coherently pumped at a frequency near the two-photon resonance frequency. A sharply resonant rise in the second- and third-level population is found for slight detuning of the pump from two-photon resonance. Population inversion in either transition is shown to be possible, depending on the pertinent parameters. This effect furnishes a novel method of population inversion at a frequency higher than the pump frequency. Keywords include: Laser, Laser-type devices, Coherent pumping, Three-level systems, and Quantum electronics.

Final Technical Report•Feb 1, 1985•0 citations

Laser oscillations

E. Rosencher, B. Vinter

Introduction We were able to show in Chapter 3 that a medium in which we can obtain a population inversion (i.e. a situation in which the population density in the excited state is greater than that in the fundamental level) allows for optical gain of an electromagnetic wave having a frequency near to the resonant frequency of the system. By introducing feedback of the amplified signal into the medium, the system can be made to oscillate naturally, resulting in laser oscillations . To obtain this population inversion, we must introduce at least a third (and perhaps even a fourth) energy level into the system. (We saw how a two-level system under the influence of an intense pump beam will saturate with no resulting population inversion.) The aim then of this chapter is to introduce the concepts necessary to extend our two-level system into a working model capable of illustrating the phenomenon of laser oscillation. We will not spend too much time discussing atomic transition lasers as they do not figure readily in our treatment of quantum electronic properties of semiconductors. An exception will be made, however; we brush upon the particular topics of a diode pumped laser in Complement 4.E and a quantum cascade laser in Complement 13.H. Population inversion and optical amplification Population inversion We will show how population inversion can be achieved by carrier transfer from higher lying levels to the upper level of a two-level subsystem of interest.

Cambridge University Press eBooks•May 30, 2002•0 citations

Photodissociation of Thallium Bromide and Cesium Bromide

William T. Walter, Steven Jarrett

Photodissociation of TlBr and CsBr by the 1850-Å mercury resonance line could lead to laser transitions at 5350 Å and 2.93 μ in Tl and Cs, respectively. The transition probabilities of Cs are such that radiative decay will maintain a population inversion between the 72P3/2 and 72S½ levels. Calculations indicate that a gain of 4% per m is expected at a temperature of 890° for photodissociation into the 72P3/2, ½ Cs levels. In Tl, however, the 62P3/2 level is metastable. A suitable quenching gas must be found before oscillation is possible at 5350 Å from photodissociation into the 72S½ level. Nitrogen and CO2 have been tried thus far without success.

Applied Optics•Jan 1, 1965•9 citations

Possibility of population inversion in a two-level system by a wide-band pump field

V. N. Lugovoǐ, V. N. Streltsov

A theoretical analysis is made of the interaction between a two-level quantum-mechanical system and an electromagnetic field which is frequency- and amplitude-modulated. Attention is drawn to the fact that, subject to certain general assumptions, the usual methods for population inversion in such a system—(2 n + l)π pulses and adiabatic inversion methods—apply also if the pump field is of the wide-band type. Exact solutions are obtained for the nature of the time dependence of the instantaneous field frequency at which a population inversion occurs under nonadiabatic conditions.

Soviet Journal of Quantum Electronics•May 31, 1976•1 citation

The Metastable 2 p 3 -State of Mercury Atoms

S. Loria

Let us consider a mixture of mercury vapor, thallium vapor and nitrogen in a closed quartz tube under well defined conditions of pressure and temperature, illuminated by λ 2537A of constant intensity. \n \nDue to the absorption of the illuminating radiation a constant number N of mercury atoms will be activated in unit time. Those activated atoms persist in the 2p2-state for a finite time t which is known to be of the order of magnitude of 10^-7 sec [1]. If they escape collision during this period they return to their normal state in the ordinary wave-emitting radiation (resonance). They may, however, while activated, collide with nitrogen molecules, normal mercury atoms or normal thallium atoms. We shall assume, for the present, that the amount of nitrogen and thallium sufficiently exceeds the amount of mercury, so that we may disregard totally the collisions between activated and normal mercury atoms. \n \nWe assume furthermore that all collisions between activated mercury atoms and thallium atoms result in the activation of the latter, producing the fluorescence radiation of thallium with a constant energy distribution between its different lines.

Proceedings of the National Academy of Sciences•Nov 1, 1925•3 citations
The method of doubled pulses was used to achieve pulsed lasing due to the 5 d 10 6 p 2 P 3/2 —5 d 9 6 s 2 2 D 5/2 transition in the mercury ion (λ = 398 nm), similar to efficient lasing transitions in copper and gold atoms. Discharge tubes with inner diameters 4 and 8 mm and 30 cm long were used. They were filled with neon or helium as the buffer gases. There was a significant difference between lasing in the narrow and wide tubes. In the wide tube it was possible to observe lasing only when the delay between the pulses was short; the beam was not ring-shaped, contrary to what was found earlier for the narrow tube. Lasing was observed even when the delay between the two pulses was less than 5 μs, but lasing disappeared when heating of the tube became stronger as the pulse repetition frequency was increased. Possible population and inversion mechanisms were analysed.
A three-level system which radiates at both intermediate transition frequencies is considered to be coherently pumped at a frequency near the two-photon resonance frequency. A sharply resonant rise in the second- and third-level population is found for slight detuning of the pump from two-photon resonance. Population inversion in either transition is shown to be possible, depending on the pertinent parameters. This effect furnishes a novel method of population inversion at a frequency higher than the pump frequency. Keywords include: Laser, Laser-type devices, Coherent pumping, Three-level systems, and Quantum electronics.
Introduction We were able to show in Chapter 3 that a medium in which we can obtain a population inversion (i.e. a situation in which the population density in the excited state is greater than that in the fundamental level) allows for optical gain of an electromagnetic wave having a frequency near to the resonant frequency of the system. By introducing feedback of the amplified signal into the medium, the system can be made to oscillate naturally, resulting in laser oscillations . To obtain this population inversion, we must introduce at least a third (and perhaps even a fourth) energy level into the system. (We saw how a two-level system under the influence of an intense pump beam will saturate with no resulting population inversion.) The aim then of this chapter is to introduce the concepts necessary to extend our two-level system into a working model capable of illustrating the phenomenon of laser oscillation. We will not spend too much time discussing atomic transition lasers as they do not figure readily in our treatment of quantum electronic properties of semiconductors. An exception will be made, however; we brush upon the particular topics of a diode pumped laser in Complement 4.E and a quantum cascade laser in Complement 13.H. Population inversion and optical amplification Population inversion We will show how population inversion can be achieved by carrier transfer from higher lying levels to the upper level of a two-level subsystem of interest.
Photodissociation of TlBr and CsBr by the 1850-Å mercury resonance line could lead to laser transitions at 5350 Å and 2.93 μ in Tl and Cs, respectively. The transition probabilities of Cs are such that radiative decay will maintain a population inversion between the 72P3/2 and 72S½ levels. Calculations indicate that a gain of 4% per m is expected at a temperature of 890° for photodissociation into the 72P3/2, ½ Cs levels. In Tl, however, the 62P3/2 level is metastable. A suitable quenching gas must be found before oscillation is possible at 5350 Å from photodissociation into the 72S½ level. Nitrogen and CO2 have been tried thus far without success.
A theoretical analysis is made of the interaction between a two-level quantum-mechanical system and an electromagnetic field which is frequency- and amplitude-modulated. Attention is drawn to the fact that, subject to certain general assumptions, the usual methods for population inversion in such a system—(2 n + l)π pulses and adiabatic inversion methods—apply also if the pump field is of the wide-band type. Exact solutions are obtained for the nature of the time dependence of the instantaneous field frequency at which a population inversion occurs under nonadiabatic conditions.
Let us consider a mixture of mercury vapor, thallium vapor and nitrogen in a closed quartz tube under well defined conditions of pressure and temperature, illuminated by λ 2537A of constant intensity. \n \nDue to the absorption of the illuminating radiation a constant number N of mercury atoms will be activated in unit time. Those activated atoms persist in the 2p2-state for a finite time t which is known to be of the order of magnitude of 10^-7 sec [1]. If they escape collision during this period they return to their normal state in the ordinary wave-emitting radiation (resonance). They may, however, while activated, collide with nitrogen molecules, normal mercury atoms or normal thallium atoms. We shall assume, for the present, that the amount of nitrogen and thallium sufficiently exceeds the amount of mercury, so that we may disregard totally the collisions between activated and normal mercury atoms. \n \nWe assume furthermore that all collisions between activated mercury atoms and thallium atoms result in the activation of the latter, producing the fluorescence radiation of thallium with a constant energy distribution between its different lines.