Inelastic collisions in laser excited alkali atoms

1987 ◽  
Author(s):  
Maria Allegrini ◽  
Silvia Gozzini ◽  
Luigi Moi
Keyword(s):  
Inelastic Collisions ◽  
Alkali Atoms

Inelastic collisions between excited alkali atoms and molecules. V. Sensitized fluorescence in mixtures of sodium with N2, H2, HD, and D2

1968 ◽  
Vol 46 (19) ◽  
pp. 2127-2131 ◽  
Author(s):  
M. Stupavsky ◽  
L. Krause
Keyword(s):  
Cross Sections ◽  
Ground State ◽  
Resonance Effect ◽  
Excitation Transfer ◽  
Inelastic Collisions ◽  
Sodium Vapor ◽  
Sensitized Fluorescence ◽  
Atoms And Molecules ◽  
Alkali Atoms ◽  
Exciting Beam

3 2P1/2 ↔ 3 2P3/2 excitation transfer in sodium, induced in inelastic collisions with ground-state N2, H2, HD, and D2 molecules, has been investigated in a series of sensitized fluorescence experiments. Mixtures of sodium vapor at a pressure of 5 × 10−7 Torr, and the gases, were irradiated with each NaD component in turn, and the fluorescence which contained both D components was monitored at right angles to the direction of the exciting beam. Measurements of the relative intensities of the NaD fluorescent components yielded the following collision cross sections for excitation transfer. For Na–N2 collisions: Q12(2P1/2 → P3/2) = 144 Å2, Q21(2P1,2 ← 2P3/2) = 76 Å2 for Na–H2 collisions: Q12 = 80 Å2, Q21 = 42 Å2. For Na–HD collisions: Q12 = 84 Å2, Q21 = 44 Å2. For Na–D2 collisions: Q12 = 98 Å2, Q21 = 52 Å2. The cross sections Q21 exhibit a slight resonance effect between the atomic and molecular rotational transitions.

Inelastic Collisions between Excited Alkali Atoms and Molecules. VIII. 62P1/2–62P3/2 Mixing and Quenching in Mixtures of Rubidium with H2, HD, D2, N2, CH4, and CD4

1973 ◽  
Vol 51 (3) ◽  
pp. 257-265 ◽  
Author(s):  
I. N. Siara ◽  
L. Krause
Keyword(s):  
Fine Structure ◽  
Cross Sections ◽  
Ground State ◽  
Inelastic Collisions ◽  
Fluorescent Intensity ◽  
Rubidium Vapor ◽  
Sensitized Fluorescence ◽  
Molecular Gases ◽  
Alkali Atoms ◽  
Intensity Ratios

Excitation transfer between the 62P fine-structure substates in rubidium, induced in inelastic collisions with ground-state molecules, has been studied using techniques of sensitized fluorescence. Rubidium vapor in mixtures with various molecular gases was irradiated with each component of the 2P rubidium doublet in turn, and measurements of sensitized-to-resonance fluorescent intensity ratios yielded the following mixing cross sections Q12(2P1/2 → 2P3/2) and Q21(2P1/2 ← 2P3/2), as well as effective quenching cross sections Q1X(2P1/2 → 2XJ″) and Q2X(2P3/2 → 2XJ″). For collisions with H2: Q12(2P1/2 → 2P3/2) = (41 ± 5) Å2; Q21(2P1/2 ← 2P3/2) = (26 ± 3) Å2; Q1X(2P1/2 → 2XJ″) = (36 ± 9) Å2; Q2X(2P3/2 → 2XJ″) = (31 ± 8) Å2. For HD: Q12 = (42 ± 5) Å2; Q21 = (27 ± 4) Å2; Q1X = (47 ± 13) Å2; Q2X = (38 ± 10) Å2. For D2: Q12 = (42 ± 5) Å2; Q21 = (27 ± 4) Å2; Q1X = (28 ± 8) Å2; Q2X = (21 ± 7) Å2. For N2: Q12 = (107 ± 15) Å2; Q21 = (70 ± 10) Å2; Q1X = (128 ± 44) Å2; Q2X = (126 ± 33) Å2. For CH4: Q12 = (38 ± 6) Å2; Q21 = (24 ± 3) Å2; Q1X = (129 ± 41) Å2; Q2X = (114 ± 37) Å2. For CD4: Q12 = (52 ± 7) Å2; Q21 = (34 ± 5) Å2; Q1X = (82 ± 30) Å2; Q2X = (76 ± 22) Å2. An analysis of these results suggests the possibility of resonances with various molecular rotational and vibrational transitions.

Inelastic Collisions Between Excited Alkali Atoms and Molecules X. Temperature Dependence of Cross Sections for 2P1/2↔2P3/2 Mixing in Cesium, Induced in Collisions with Deuterated Hydrogens, Ethanes, and Propanes

1974 ◽  
Vol 52 (7) ◽  
pp. 589-591 ◽  
Author(s):  
E. Walentynowicz ◽  
R. A. Phaneuf ◽  
L. Krause
Keyword(s):  
Energy Transfer ◽  
Temperature Dependence ◽  
Isotope Effect ◽  
Cross Sections ◽  
Rotational Energy ◽  
Inelastic Collisions ◽  
Atoms And Molecules ◽  
Rotational Energy Transfer ◽  
Alkali Atoms ◽  
The Cross

The dependence on temperature of the cross sections for 2P1/2 ↔ 2P3/2 mixing in cesium, induced in collisions with various deuterated hydrogen, ethane and propane molecules, has been studied in the range 290–650 K. In the cases of hydrogen and ethane, the behavior of the cross sections was found to depend on the degree of deuteration of the molecules. The very large sizes of the mixing cross sections and the isotope effect observed in their variation with temperature, are ascribed to the phenomenon of electronic to rotational energy transfer.

Inelastic collisions between excited alkali atoms and molecules. VII. Sensitized fluorescence and quenching in mixtures of rubidium with H2, HD, D2, N2, CH4, CD4, C2H4, and C2.H6

1970 ◽  
Vol 48 (22) ◽  
pp. 2761-2768 ◽  
Author(s):  
E. S. Hrycyshyn ◽  
L. Krause
Keyword(s):  
Cross Sections ◽  
Photon Counting ◽  
Inelastic Collisions ◽  
Exciting Light ◽  
Rubidium Vapor ◽  
Sensitized Fluorescence ◽  
Alkali Atoms ◽  
Order Of Magnitude ◽  
Resonance Doublet ◽  
Intensity Ratios

52P1/2 ↔ 52P3/2 mixing and 52S1/2 ← 52P1/2, 2P3/2 quenching in rubidium, induced in collisions with ground state H2, HD, D2, N2, CH4, CD4, C2H4, and C2H6 molecules, have been investigated using methods of sensitized fluorescence. The rubidium vapor mixed with each of the gases was excited in turn by each component of the rubidium resonance doublet, and the resulting fluorescence, emitted at right angles to the direction of the exciting light, was resolved into the two fine-structure components whose intensity ratios were measured in relation to the gas pressure using photon counting techniques. The measurements yielded the following cross sections for the mixing and quenching collisions.For H2: Q12(2P1/2 → 2P3/2) = 11 Å2, Q21(2P1/2 ← 2P3/2) = 15 Å2, Q10(2S1/2 ← 2P1/2) = 6 Å2, Q20(2S1/2 ← 2P3/2) = 3 Å2.[Formula: see text]The mixing cross sections agree with theoretical values within an order of magnitude.

Inelastic collisions between excited alkali atoms and molecules. VI. Sensitized fluorescence in mixtures of sodium with CH4, CD4, C2H2, C2H4, and C2H6

1969 ◽  
Vol 47 (12) ◽  
pp. 1249-1252 ◽  
Author(s):  
M. Stupavsky ◽  
L. Krause
Keyword(s):  
Cross Sections ◽  
Inelastic Collisions ◽  
Fluorescent Light ◽  
Molecular Gas ◽  
Sodium Vapor ◽  
Total Cross Sections ◽  
Sensitized Fluorescence ◽  
Alkali Atoms ◽  
The Cross ◽  
Good Agreement

The total cross sections for 32P1/2–32P3/2 mixing in sodium, induced in collisions with CH4, CD4, C2H2, C2H4, and C2H6 molecules, have been determined using the method of sensitized fluorescence. The sodium vapor – molecular gas mixtures were irradiated with each NaD component in turn, and the cross sections were obtained from measurements of relative intensities of the two D components present in the fluorescent light. The cross sections are as follows. For CH4: Q12(2P1/2 → 2P3/2) = 148 Å2, Q21(2P1/2 ← 2P3/2) = 77 Å2; for CD4: Q12 = 151 Å2, Q21 = 81 Å2; for C2H2: Q12 = 182 Å2, Q21 = 96 Å2; for C2H4: Q12 = 178 Å2, Q21 = 94 Å2; for C2H6: Q12 = 182 Å2, Q21 = 95 Å2. The cross sections Q21 are in good agreement with the values calculated according to the theory of Callaway and Bauer.

Inelastic collisions between excited alkali atoms and molecules. IV. Sensitized fluorescence and quenching in mixtures of cesium with N2, H2, HD, and D2

1968 ◽  
Vol 46 (9) ◽  
pp. 1051-1057 ◽  
Author(s):  
D. A. McGillis ◽  
L. Krause
Keyword(s):  
Vapor Pressure ◽  
Multiple Scattering ◽  
Cross Sections ◽  
Ground State ◽  
Inelastic Collisions ◽  
Cesium Vapor ◽  
Sensitized Fluorescence ◽  
Alkali Atoms ◽  
Exciting Beam ◽  
Resonance Doublet

6 2P1/2 ↔ 6 2P3/2 mixing and 6 2S1/2 ← 6 2P1/2,3/2 quenching in cesium, induced in collisions with ground state N2, H2, HD, and D2 molecules, have been investigated using techniques of sensitized fluorescence. Mixtures of cesium vapor and the gases, in which the cesium vapor pressure was kept very low to avoid multiple scattering, were irradiated with each component of the cesium resonance doublet in turn. The fluorescence which contained both components of the doublet was observed in a direction perpendicular to that of the exciting beam. Measurements of the relative intensities of the fluorescent components yielded the following cross sections for mixing and quenching. For Cs–N2 collisions: Q12(2P1/2 → 2P3/2) = 4.7 Å2, Q21(2P1/2 ← 2P3/2) = 25 Å2, Q10(2S1/2 ← 2P1/2) = 77 Å2, Q20(2S1/2 ← 2P3/2) = 69 Å2. For Cs–H2 collisions: Q12 = 6.7 Å2, Q21 = 44 Å2, Q10 = 7 Å2, Q20 = 5 Å2. For Cs–HD collisions: Q12 = 4.8 Å2, Q21 = 32 Å2, Q10 = 4 Å2, Q20 = 3 Å2. For Cs–D2 collisions: Q12 = 4.2 Å2, Q21 = 28 Å2, Q10 = 8 Å2, Q20 = 7 Å2. The Cs–N2 and Cs–H2 cross sections supersede the values published previously (McGillis and Krause 1967). The cross sections Q21 appear to exhibit resonances with molecular rotational transitions.

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