EUV emission spectra of charge-selected Sn ions
in charge exchange spectroscopy
H. Tanuma, H. Ohashi, A. Sasaki, S. Fujioka**, H. Nishimura** and K. Nishihara**
Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397, Japan
*Advanced Photon Reserch Center, Japan Atomic Energy Agency, Kyoto 619-0215, Japan
**Institute for Laser Engineering, Osaka University, Osaka 565-0871, Japan
Charge Exchange Spectroscopy
CCD image
ECR ion source
Observation of EUV emission spectra from the individual
charge states of Sn ions in charge transfer collisions of
multiply charged Sn ions with neutral gas targets to
provide spectroscopic data which are necessary for
understanding of the high power EUV light source.
Analyzing Magnet
Analyzing Magnet
Ion Beam
Snq+ (q = 5-15)
Switching Magnet
Differential
Pumping
Spectrometer
Target Gas
Snq+ + Rg → Sn(q-1)+* + Rg+
←
14.25 GHz ECR
Ion source
CCD
He, Xe, etc.
Δλ ≥ 0.03 nm
photon emission
Sn(q-1)+
FC
Rg : rare gas target = He and Xe
TMP
Liq. N2 cooled CCD
TMP
Fig. 1.Schematic diagram and photograph of the experimental
setup in Tokyo Metropolitan University.
Collision Chamber
Grazing Incident Spectrometer
Experimental Results
4d-5f
4
6
8
Sn15+-He
4p-4d
10
12
14
16
18
20
4d-5f
22
4
6
8
10
4d-4f
4p-4d
4d-5p
4d-5f
4
6
8
10
12
14
16
18
18
20
Intensity / arb. units
4d-4f
12
14
16
18
20
22
24
26
8
Sn12+-He
?
10
12
14
16
18
20
24
5
Sn10+-Xe
4d-5f
4d-4f
?
6
8
10
4d-5p
4d-5f
4d-4f
12
14
16
18
Sn10+-He
2nd
20
22
24
26
4d-4f
4p-4d
4d-5p
4d-5f
4d-6f
4p-4d
4d-6p
8+
Sn -Xe
4d-5p
4d-5f
?
Sn9+-He
2nd
10
15
12
14
16
18
20
22
24
4d-4f
8+
Sn -He
26
6
8
10
12
Wavelength / nm
4d-5p
4d-4f
?
Sn7+-Xe
Sn7+-Ar
4p-4d
Sn7+-He
10
15
20
25
30
Wavelength / nm
14
16
18
20
22
24
35
4d-4f
4p-4d
4d-5p
4d-5f
Sn5+
Intensity / arb. units
Intensity / arb. units
4d-5f
35
5
40
10
15
20
25
30
35
40
Wavelength / nm
with He and Xe.
26
Wavelength / nm
4d-4f
4p-4d
4d-5p
4d-5f
Sn6+
30
4d-5p
4d-5f
Sn6+-Xe
15
20
Sn8+-He
Sn VIII
19
4d-4f
20
21
22
23
Wavelength / nm
Sn6+-He
10
Comparison with sparks
Intensity / arb. units
10
25
• Differen target gas gives different population
distribution in the excited states produced in the
charge exchange reaction.
○ : Xe target
12
● : He target
• However, the wavelengths of the peaks don't
◇ : HULLAC
depend on the targets in this experiment.
10
• Prominent peaks in observed emission spectra have
8
been identified by comparison with the theoretical
4d-5p
results by using the HULLAC code.
4d-5f
6
• The averaged wavelengths of transitions shows
4d-4f
good agreement between the experiments and the
4
theoretical calculations for the 4d-5p and 4d-5f
5
10
15
20
25
30
35
40
transitions.
Wavelength / nm
• Oh the other hand, the 4d-4f transitions have
Fig. 4. Charge-state dependence of averaged
approximately constant differences about 0.5 nm
transition wavelengths of Sn ions. Here we
assume that the emissions are due to Sn(q-1)+
between the experiment and the calculation as in
ions produced by the single electron capture
results for Xe ions.
q+
Intensity / arb. units
8
20
4d-5p
4d-4f
5
Fig. 3. Charge-state dependence of EUV emission spectra in collisions of Snq+ (5 ≤ q ≤ 15)
ions with He and Xe at 20q keV.
in collisions of Sn
6
4d-5f
6
14
Sn7+
Sn9+-Xe
8
q=7
Discussion
Wavelength / nm
4d-4f
4p-4d
4d-5p
4d-5f
9
Wavelength / nm
26
4d-5p
Intensity / arb. units
Intensity / arb. units
22
4d-4f
4p-4d
4d-5p
4d-5f
Wavelength / nm
Sn8+
8
10
Snq+ - He
Sn11+-He
10
4d-5p
Snq+ - Xe
11
4d-4f
Sn9+
4d-5f
12
6
Wavelength / nm
Sn11+-Xe
13
12
9
4d-5f
4d-4f
6
4d-4f
4p-4d
4d-5p
4d-5f
14
10
Sn12+-Xe
4d-5f
22
4d-5p
8
22
q = 15
13
11
4d-5p
Sn13+-He
Sn10+
6
20
4d-4f
14
q=7
Wavelength / nm
Intensity / arb. units
16
4d-4f
4p-4d
4d-5p
4d-5f
Intensity / arb. units
Intensity / arb. units
4d-4f
4p-4d
14
Sn11+
Sn13+-Xe
4d-5p
12
Wavelength / nm
Sn12+
4d-5f
Sn14+-He
4p-4d
4d-5p
q = 15
Sn14+-Xe
4d-4f
Wavelength / nm
4d-4f
Intensity / arb. units
4d-4f
4d-5p
Intensity / arb. units
Sn15+-Xe
4d-5p
Charge state of Sn ions
4d-5p
4d-4f
4p-4d
4d-5p
4d-5f
Sn13+
4d-4f
4p-4d
4s-4p
Intensity / arb. units
Intensity / arb. units
Sn14+
25
30
35
Wavelength / nm
Fig. 2. Target dependence of EUV emission spectra in collisions of
Snq+ (6 ≤ q ≤ 15) ions with He and Xe at 20q keV. Relative transition
probabilities of Sn(q-1)+ ions calculated with the HULLAC code are
also shown. Tentative identifications of transitions have been done
by comparison with the theoretical results.
24
25
Sn6+-He
Sn VI
27
28
29
30
31
32
33
Wavelength / nm
References
Sn VIII :
V. I. Azarov and Y. N. Joshi,
J. Phys. B 26 (1993) 3495.
Sn VI :
Y. N. Joshi and Th. A. M. van Kleef,
Can. J. Phys. 55 (1977) 714.
Fig. 5. EUV emission spectra from vacuum sparks and those
in this work.
• Emission spectra from vacuum sparks show qualitatively good agreements with those in
the charge exchange spectroscopy.
• This finding indicates that the charge exchange spectroscopy is very useful technique to
analyze radiation from plasmas.
• The reason of this agreement must be investigated much further.
Acknowledgment : The authors are grateful for discussions with F. Koike, T. Kagawa, T. Kato, and other members of the working group for the EUV modeling. This work was financially supported in part by
MEXT (Ministry of Education, Culture, Sports, Science and Technology, Japan) under contract subject “Leading Project for EUV lithography source development’”.