Adaptive optics systems using sodium laser guide stars are widely
employed at major astronomical observatories. It is natural to ask
whether other atomic species might offer advantages. In this paper, we
review all abundant atoms and ions in the upper atmosphere, including
Na, Fe, ${\rm{M}}{{\rm{g}}^
+}$, ${\rm{S}}{{\rm{i}}^
+}$, ${\rm{C}}{{\rm{a}}^
+}$, and K and also the non-metallic
species N, ${{\rm{N}}^
+}$, O, and H, considering their
potential for adaptive optics. Return fluxes for all transitions that
can be excited using either one or two wavelengths were computed. We
also considered multi-wavelength emission, comparing the performance
of different transitions for polychromatic laser guide star (PLGS)
adaptive optics. We find that of all the mesospheric metals, Na is the
most suitable for both monochromatic laser guide stars and PLGSs,
providing about six times more return flux than the best transitions
in Fe. For high-altitude observatories, excitation at 330 nm in Na
should give the highest PLGS performance. Atomic O, N, and ${{\rm{N}}^
+}$ have strong transitions and very high
abundances in the mesosphere. This makes them potential candidates for
the generation of intense laser guide stars by amplified spontaneous
emission, if a suitable excitation process can be demonstrated. Direct
excitation by CW lasers is impractical, as all transitions from the
ground state are beyond the atmospheric cutoff. Nevertheless, it may
be possible using high-power pulsed lasers.
Renaud Foy, Michel Tallon, Isabelle Tallon-Bosc, Eric Thiébaut, Jérôme Vaillant, Françoise-Claude Foy, Daniel Robert, Herb Friedman, François Biraben, Gilbert Grynberg, Jean-Pierre Gex, Alain Mens, Arnold Migus, Jean-Marc Weulersse, and David J. Butler J. Opt. Soc. Am. A 17(12) 2236-2242 (2000)
Data underlying the results presented in this paper are available in [24,28]. Selected data for strong transitions in the atomic species
discussed here are available from the authors upon request.
24. A. E. Hedin, “Extension of the MSIS
thermosphere model into the middle and lower
atmosphere,” J. Geophys. Res. 96, 1159–1172
(1991). [CrossRef]
28. A. Kramida, Y. Ralchenko, J. Reader, and NIST ASD
Team, “NIST atomic spectra database (ver.
5.8),” 2020, https://physics.nist.gov/asd.
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All transitions having $q \gt
0.4$ and ${\lambda
_{{\rm{ex}}}} \ge 300 \;{\rm{nm}}$ are listed.
Table 5.
Na I Transitions for a PLGS Employing Two-Step Excitationa
(nm)
(nm)
(nm)
588.995
0.79
18.55
330.237
19.41
2337.915
19.95
0.79
18.59
330.237
19.41
2205.647
19.79
0.75
19.74
330.237
19.41
1140.377
19.62
0.67
19.74
330.237
19.41
1138.144
19.32
0.55
26.69
330.237
19.41
568.820
20.19
0.51
25.84
330.237
19.41
589.592
19.32
0.45
60.81
568.820
20.19
2337.915
19.95
588.995
20.78
589.592
0.71
18.56
330.298
19.32
2334.843
19.86
0.71
18.60
330.298
19.32
2208.370
19.70
0.67
19.75
330.298
19.32
1140.377
19.60
0.66
19.75
330.298
19.32
1138.144
19.30
0.59
18.56
330.298
19.32
2337.896
19.16
0.51
25.87
330.298
19.32
588.995
19.82
0.49
18.60
330.298
19.32
2205.647
19.00
0.49
26.71
330.298
19.32
568.819
19.40
0.49
26.73
330.298
19.32
568.263
20.10
0.41
60.69
568.263
20.10
2334.843
19.86
589.592
20.65
588.995
0.57
18.56
330.298
19.13
2334.843
19.67
0.57
18.60
330.298
19.13
2208.370
19.51
0.54
19.75
330.298
19.13
1140.377
19.41
0.53
19.75
330.298
19.13
1138.144
19.11
0.48
18.56
330.298
19.13
2337.896
18.97
0.41
25.85
330.298
19.13
589.592
19.98
0.40
18.60
330.298
19.13
2205.647
18.81
0.40
26.71
330.298
19.13
568.819
19.21
0.40
26.73
330.298
19.13
568.263
19.91
588.995
20.96
330.237
0.51
18.56
330.298
19.03
2334.843
19.57
0.51
18.60
330.298
19.03
2208.370
19.41
0.51
18.60
330.298
19.03
2205.647
19.64
0.48
19.75
330.298
19.03
1140.377
19.66
0.48
19.75
330.298
19.03
1138.144
19.36
0.43
18.56
330.298
19.03
2337.896
18.87
330.237
19.25
588.995
0.50
126.58
589.592
20.68
818.326
20.68
0.23
126.21
589.592
20.68
819.479
19.99
588.995
20.91
589.592
0.50
83.39
588.995
20.31
1140.377
20.31
0.35
83.50
588.995
20.31
1138.144
20.01
589.592
20.87
588.995
0.49
18.27
330.237
18.99
5426.880
19.01
0.49
18.28
330.237
18.99
5013.920
19.30
0.49
18.59
330.237
18.99
2205.647
19.37
0.47
19.09
330.237
18.99
1477.974
19.49
0.46
19.74
330.237
18.99
1140.377
19.30
0.46
19.74
330.237
18.99
1138.144
18.99
588.995
20.78
589.592
0.47
18.37
330.237
18.94
3414.261
19.49
0.47
18.37
330.237
18.94
3407.755
19.19
0.46
18.59
330.237
18.94
2208.370
19.03
0.46
18.59
330.237
18.94
2205.647
19.33
0.44
19.74
330.237
18.94
1140.377
19.33
0.44
19.74
330.237
18.94
1138.144
19.03
589.592
20.86
588.995
0.44
18.37
330.237
18.88
3414.261
19.42
0.44
18.37
330.237
18.88
3407.755
19.12
0.43
18.59
330.237
18.88
2208.370
18.96
0.43
18.59
330.237
18.88
2205.647
19.26
0.41
19.74
330.237
18.88
1140.377
19.26
0.40
19.74
330.237
18.88
1138.144
18.96
588.995
21.03
589.592
0.44
18.28
330.298
18.88
5434.170
18.92
0.44
18.29
330.298
18.88
5007.670
19.21
0.43
18.60
330.298
18.88
2208.370
19.26
0.42
19.10
330.298
18.88
1476.749
19.40
0.40
19.75
330.298
18.88
1140.377
19.28
0.40
19.75
330.298
18.88
1138.144
18.98
589.592
20.66
330.237
0.40
60.81
568.820
20.08
2337.915
19.85
330.237
19.26
All transitions having $q \gt
0.4$ and ${\lambda
_{{\rm{ex}}}} \ge 300 \;{\rm{nm}}$ are listed. The last line
for each excitation scheme shows the return flux
coefficient for the first excitation wavelength.
Table 6.
Fe I Transitions for Monochromatic LGS Employing Two-Step
Excitationa
(nm)
(nm)
355.492
19.32
314.399
19.31
381.764
19.29
380.198
19.08
All transitions having $\log\;
(\varepsilon) \gt 19$ and ${\lambda
_{{\rm{ex}}}} \ge 300 \;{\rm{nm}}$ are listed.
Table 7.
Fe I Transitions for a PLGS Employing One-Step Excitationa
(nm)
(nm)
(nm)
319.323
0.10
26.39
319.323
17.90
517.160
17.90
All transitions having $q \gt
0.1$ and ${\lambda
_{{\rm{ex}}}} \ge 300 \;{\rm{nm}}$ are listed.
Table 8.
Fe I Transitions for a PLGS Employing Two-Step Excitationa
(nm)
(nm)
(nm)
437.593
0.12
25.41
361.207
18.17
973.857
18.01
0.11
27.33
371.993
18.85
973.857
18.01
437.593
16.06
385.991
0.12
40.78
371.993
18.49
561.564
18.49
0.10
44.57
371.993
18.49
532.418
18.38
385.991
18.18
All transitions having a de-excitation $q \gt
0.1$ and ${\lambda
_{{\rm{ex}}}} \ge 300 \;{\rm{nm}}$ are listed. In brackets
in the last line for each excitation scheme, the return
flux coefficient for the first excitation wavelength is
shown.
Table 9.
Ca I Transitions for Monochromatic LGS Employing Two-Step
Excitation Having Wavelength and Return-Flux Coefficient
(nm)
(nm)
585.745
19.07
−3.43
430.774
19.01
−3.35
Table 10.
Mean Collision Cross Sections
Cross Section ()
Atom
Mass (amu)
Radius (nm)
Ar
Na
22.990
0.191
0.565
0.550
0.277
Fe
55.845
0.127
0.315
0.303
0.171
Mg
24.305
0.162
0.443
0.429
0.226
Si
28.085
0.109
0.257
0.247
0.145
Ca
40.078
0.197
0.593
0.577
0.288
K
39.098
0.237
0.790
0.771
0.370
N
14.007
0.070
0.152
0.144
0.097
O
15.999
0.066
0.143
0.135
0.093
Ar
39.948
0.106
0.248
0.238
0.141
H
1.008
0.070
0.152
0.144
0.097
Table 11.
Collision Rates, in Units of , for Metallic Species
Altitude (km)
Ca
Fe
K
Mg
Na
Si
75
2449
1219
3283
2062
2675
1150
80
1108
551.7
1486
933.3
1211
520.7
85
484.1
241.0
649.1
407.7
528.8
227.5
90
203.7
101.4
273.1
171.5
222.5
95.70
95
82.66
41.15
110.8
69.60
90.28
38.84
100
32.65
16.26
43.77
27.49
35.65
15.34
105
13.08
6.515
17.54
11.01
14.28
6.147
110
5.662
2.821
7.590
4.766
6.181
2.661
115
2.740
1.365
3.673
2.306
2.991
1.288
120
1.489
0.742
1.996
1.253
1.625
0.700
Table 12.
Collision Rates, in Units of , for Non-Metallic Species
All transitions having $q \gt
0.4$ and ${\lambda
_{{\rm{ex}}}} \ge 300 \;{\rm{nm}}$ are listed.
Table 5.
Na I Transitions for a PLGS Employing Two-Step Excitationa
(nm)
(nm)
(nm)
588.995
0.79
18.55
330.237
19.41
2337.915
19.95
0.79
18.59
330.237
19.41
2205.647
19.79
0.75
19.74
330.237
19.41
1140.377
19.62
0.67
19.74
330.237
19.41
1138.144
19.32
0.55
26.69
330.237
19.41
568.820
20.19
0.51
25.84
330.237
19.41
589.592
19.32
0.45
60.81
568.820
20.19
2337.915
19.95
588.995
20.78
589.592
0.71
18.56
330.298
19.32
2334.843
19.86
0.71
18.60
330.298
19.32
2208.370
19.70
0.67
19.75
330.298
19.32
1140.377
19.60
0.66
19.75
330.298
19.32
1138.144
19.30
0.59
18.56
330.298
19.32
2337.896
19.16
0.51
25.87
330.298
19.32
588.995
19.82
0.49
18.60
330.298
19.32
2205.647
19.00
0.49
26.71
330.298
19.32
568.819
19.40
0.49
26.73
330.298
19.32
568.263
20.10
0.41
60.69
568.263
20.10
2334.843
19.86
589.592
20.65
588.995
0.57
18.56
330.298
19.13
2334.843
19.67
0.57
18.60
330.298
19.13
2208.370
19.51
0.54
19.75
330.298
19.13
1140.377
19.41
0.53
19.75
330.298
19.13
1138.144
19.11
0.48
18.56
330.298
19.13
2337.896
18.97
0.41
25.85
330.298
19.13
589.592
19.98
0.40
18.60
330.298
19.13
2205.647
18.81
0.40
26.71
330.298
19.13
568.819
19.21
0.40
26.73
330.298
19.13
568.263
19.91
588.995
20.96
330.237
0.51
18.56
330.298
19.03
2334.843
19.57
0.51
18.60
330.298
19.03
2208.370
19.41
0.51
18.60
330.298
19.03
2205.647
19.64
0.48
19.75
330.298
19.03
1140.377
19.66
0.48
19.75
330.298
19.03
1138.144
19.36
0.43
18.56
330.298
19.03
2337.896
18.87
330.237
19.25
588.995
0.50
126.58
589.592
20.68
818.326
20.68
0.23
126.21
589.592
20.68
819.479
19.99
588.995
20.91
589.592
0.50
83.39
588.995
20.31
1140.377
20.31
0.35
83.50
588.995
20.31
1138.144
20.01
589.592
20.87
588.995
0.49
18.27
330.237
18.99
5426.880
19.01
0.49
18.28
330.237
18.99
5013.920
19.30
0.49
18.59
330.237
18.99
2205.647
19.37
0.47
19.09
330.237
18.99
1477.974
19.49
0.46
19.74
330.237
18.99
1140.377
19.30
0.46
19.74
330.237
18.99
1138.144
18.99
588.995
20.78
589.592
0.47
18.37
330.237
18.94
3414.261
19.49
0.47
18.37
330.237
18.94
3407.755
19.19
0.46
18.59
330.237
18.94
2208.370
19.03
0.46
18.59
330.237
18.94
2205.647
19.33
0.44
19.74
330.237
18.94
1140.377
19.33
0.44
19.74
330.237
18.94
1138.144
19.03
589.592
20.86
588.995
0.44
18.37
330.237
18.88
3414.261
19.42
0.44
18.37
330.237
18.88
3407.755
19.12
0.43
18.59
330.237
18.88
2208.370
18.96
0.43
18.59
330.237
18.88
2205.647
19.26
0.41
19.74
330.237
18.88
1140.377
19.26
0.40
19.74
330.237
18.88
1138.144
18.96
588.995
21.03
589.592
0.44
18.28
330.298
18.88
5434.170
18.92
0.44
18.29
330.298
18.88
5007.670
19.21
0.43
18.60
330.298
18.88
2208.370
19.26
0.42
19.10
330.298
18.88
1476.749
19.40
0.40
19.75
330.298
18.88
1140.377
19.28
0.40
19.75
330.298
18.88
1138.144
18.98
589.592
20.66
330.237
0.40
60.81
568.820
20.08
2337.915
19.85
330.237
19.26
All transitions having $q \gt
0.4$ and ${\lambda
_{{\rm{ex}}}} \ge 300 \;{\rm{nm}}$ are listed. The last line
for each excitation scheme shows the return flux
coefficient for the first excitation wavelength.
Table 6.
Fe I Transitions for Monochromatic LGS Employing Two-Step
Excitationa
(nm)
(nm)
355.492
19.32
314.399
19.31
381.764
19.29
380.198
19.08
All transitions having $\log\;
(\varepsilon) \gt 19$ and ${\lambda
_{{\rm{ex}}}} \ge 300 \;{\rm{nm}}$ are listed.
Table 7.
Fe I Transitions for a PLGS Employing One-Step Excitationa
(nm)
(nm)
(nm)
319.323
0.10
26.39
319.323
17.90
517.160
17.90
All transitions having $q \gt
0.1$ and ${\lambda
_{{\rm{ex}}}} \ge 300 \;{\rm{nm}}$ are listed.
Table 8.
Fe I Transitions for a PLGS Employing Two-Step Excitationa
(nm)
(nm)
(nm)
437.593
0.12
25.41
361.207
18.17
973.857
18.01
0.11
27.33
371.993
18.85
973.857
18.01
437.593
16.06
385.991
0.12
40.78
371.993
18.49
561.564
18.49
0.10
44.57
371.993
18.49
532.418
18.38
385.991
18.18
All transitions having a de-excitation $q \gt
0.1$ and ${\lambda
_{{\rm{ex}}}} \ge 300 \;{\rm{nm}}$ are listed. In brackets
in the last line for each excitation scheme, the return
flux coefficient for the first excitation wavelength is
shown.
Table 9.
Ca I Transitions for Monochromatic LGS Employing Two-Step
Excitation Having Wavelength and Return-Flux Coefficient
(nm)
(nm)
585.745
19.07
−3.43
430.774
19.01
−3.35
Table 10.
Mean Collision Cross Sections
Cross Section ()
Atom
Mass (amu)
Radius (nm)
Ar
Na
22.990
0.191
0.565
0.550
0.277
Fe
55.845
0.127
0.315
0.303
0.171
Mg
24.305
0.162
0.443
0.429
0.226
Si
28.085
0.109
0.257
0.247
0.145
Ca
40.078
0.197
0.593
0.577
0.288
K
39.098
0.237
0.790
0.771
0.370
N
14.007
0.070
0.152
0.144
0.097
O
15.999
0.066
0.143
0.135
0.093
Ar
39.948
0.106
0.248
0.238
0.141
H
1.008
0.070
0.152
0.144
0.097
Table 11.
Collision Rates, in Units of , for Metallic Species
Altitude (km)
Ca
Fe
K
Mg
Na
Si
75
2449
1219
3283
2062
2675
1150
80
1108
551.7
1486
933.3
1211
520.7
85
484.1
241.0
649.1
407.7
528.8
227.5
90
203.7
101.4
273.1
171.5
222.5
95.70
95
82.66
41.15
110.8
69.60
90.28
38.84
100
32.65
16.26
43.77
27.49
35.65
15.34
105
13.08
6.515
17.54
11.01
14.28
6.147
110
5.662
2.821
7.590
4.766
6.181
2.661
115
2.740
1.365
3.673
2.306
2.991
1.288
120
1.489
0.742
1.996
1.253
1.625
0.700
Table 12.
Collision Rates, in Units of , for Non-Metallic Species