Noie
Indian I Phys. 82(10) 1395-1397(2008)
Double photoionization of Ar (Is
22s
22p
63s
23p
6) %
R Kumar*, R P K Ray and S N Tiwary
University Department of Pnysics, BRA Bihar University, Muzaffarpur-842 001, Bihar, India
E-mail : rajesh3muz@yahoo.com
Received 12 September 2007, accepted 16 June 2008
Abstract : We have calculated the double photoionization cross section (DPICS) of Ar (1 s2 2s? 2pP 3s2 3ff)
1S*0 employing the configuration interaction (CI) wave function for the ground state and Brauner, Briggs and Klar (BBK) double continuum wave function (DCWF) for the final state involved in the electric dipole transition matrix element exactly in the same as we did in our earlier work (S N Tiwary and R Kumar Indian J. Phys, 78 1095 (2004)). Comparison is made with other available experimental and theoretical results. Our present calculated result is encouraging.
Keywords : Atom, photon, photoionization PACSNo. : 31.10.
Double photoionization (DPI) consists in the absorption of a single photon by an atom or ion followed by ejection of two electrons. The interaction of a photon with each electron is independent from the others so that double photoionization is a forbidden process unless electron-electron interaction, i.e., electron correlation, is taken into account.
The subject of double photoionization of noble-gas atoms has been of growing interest to both experimentalists and theorists because double-electron photoionization in noble gases gives basic information on the electron correlation in atomic targets.
Several experimental observations and theoretical predictions have been made in heavier noble gas atoms [1-6]. Schartner et al [7,8] have measured the double photoionization cross sections of argon atomic system (Ar) from the threshold to 120 eV. Carter and Kelly [9] has performed theoretical calculation in both length and velocity form in the entire energy range of experimental data available. There is a reasonably good agreement in low energy region but considerable discrepancy exists in the high energy
w
'Corresponding Author © 2008 IACS
1396 R Kumar, RPKRay and S N Tiwary
region. Our earlier results of He [10] using Brauner, Briggs and Klar (BBK) [11] double continuum wave function (DCWF) has encouraged to extend to calculate the double photoionization cross section of Ar treating incident radiation linearly polarized in the Z-direction.
We have performed theoretical calculations for the double photoionization cross section (DPICS) of Ar by single photon impact employing the configuration interaction (CI) wave function generated exactly in the same way as Tiwary et al [12] did using the computer programme CIV3 of Hibbert [13] for the ground state and BBK double continuum wave function for the final state in both the length and velocity forms of the electric dipole matrix elements in the incident energy range from threshold to 120 eV exactly in the same way as in our earlier work [10].
Figure 1 displays our present calculated DPICS of both length (aL) and velocity (av) forms along with other available relevant theoretical results of Carter and Kelly [9]
as well as two experimental results of Schartner et al [7,8]. Comparison shows that the values obtained from the length formulation tend to lie higher than those obtained using velocity formulation in the entire energy range of our present consideration which agrees with the prediction of Carter and Kelly as well as our earlier work on the DPICS of He [10]. It is clear from figure that our velocity form results as compared to length form results tend to lie close to experimental curves which agrees with the results of Carter and Kelly. It is also clear from figure that our results and results of Carter and Kelly are reasonably in good agreement'with experimental observations in the low energy region but differ considerably in the high energy region which suggest further experimental investigation. Our present theoretical curves compared to theoretical curves of Carter and Kelly tends to lie closer to experimental curves in the entire energy range which is encouraging.
<rL (Present Result)
Figure 1. Double photoionization cross section for Argon (Ar). O K H Schartner et al (Ret. 8); #KHSchartner et al (Rat. 8); Carter and Kelly (Length) (Ref. 9); Carter and Kelly (Velocity) (Ref. 9); - • - • - Present result (Length) and Present result (Velocity).
Double photoionization ofAr (1$? %? 2p* 3s? 3p*) %
References
[1] J Colan, M S Pindzola and F Robicheaux J. Phys. B: At MoL Opt Phys. 34 L547 (2001) [2] P Selles, L Malegat and A K Kazansky Phys. Rev. A65 032711 (2002)
[3] S N Tiwary, R Kumar and R P K Ray CAMP BRABU, Muzaffarpur, India (2003) [4] S N Tiwary and U Becker CAMP BRABU, Muzaffarpur, India (2003)
[5] R Kumar, R P K Ray and S N Tiwary NCAMP, PRL Ahmedabad (2004) [6] S N Tiwary, R Kumar and R P K Ray (ICPEAC) Rosario, Argentina (2005) [7] K H Schartner ICPEAC XVI (1990)
[8] K H Schartner, P Lenz, B Mdbus, H Schmoranzer and M WikJberger Phys. Lett 128A 374 (1998) [9] S L Carter and H P Kelly Phys. Rev. A161525 (1977)
[10] S N Tiwary and R Kumar Indian J. Phys. 78 1095 (2004) [11] M Brauner, J S Briggs and H Klar J. Phys. B22 2265 (1989) [12] S N Tiwary, A E Kingston and A Hibbert J. Phys. B16 2457 (1983) [13] A Hibbert Comput Phys. Commun. 9 141 (1975)
Indian J. Phys. 82 (10), 1399-1400 (2008)
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