5 IV. CONCLUSION A plane polarized laser, polarized parallel to the axis of the linear tri-atomic negative ion, is used to investigate the behavior of the detached electron from a triatomic negative ion. A simple analytical formula for the total cross section is obtained which shows strong oscillations in contrast to the case reported in [1]. Closed orbit theory is used to explain these oscillations as the interference between detached-electron waves produced from one center and sources at the other two centers. Fourier transformation in Fig. 3 shows that these two types of orbits are responsible for the oscillations in the total photodetachment cross section and hence there are two oscillation frequencies in the three-center system in contrast to only one oscillation frequency in the two-center system. Our theoretical study suggests that the photodetachment of negative ion as a three-center model is interesting, and the interference can be used to investigate structural information of linear triatomic negative ions. However this model can optimally be modified for non-linear triatomic ions. [1] Afaq A, Ahmad I, Ahmad M A, Rashid A, Tahir B A, and Hussain M T 2009 Appl. Phys. Lett. 94 041125 [2] Afaq A and Du M L 2009 J. Phys. B: At. Mol. Opt. Phys. 42 105101 [3] Yang B C and Du M L 2010 J. Phys. B: At. Mol. Opt. Phys. 43 035002 [4] Afaq A and Du M L 2008 Commun. Theor. Phys. 50 1401 [5] Afaq A and Du M L 2006 Commun. Theor. Phys. 46 119 [6] Bivona S, Bonanno G, Burlon R, Gurrera D and Leone C 2008 Phys. Rev. A 77 051404(R) [7] Bergues B, Ansari Z, Hanstorp D and Kiyan I Y 2007 Phys. Rev. A 75 063415 [8] Bergues B and Kiyan I Y 2008 Phys. Rev. Lett. 100 143004 [9] Wells J E and Yukich J N 2009 Phys. Rev. A 80 055403 [10] Walter C W, Gibson N D, Field R L, Snedden A P, Shapiro J Z, Janczak C M and Hanstorp D 2009 Phys. Rev. A 80 014501 [11] Andersson P, Lindahl A O, Hanstorp D and Pegg D J 2009 Phys. Rev. A 79 022502 [12] Pernpointner M, Rapps T and Cederbaum L S 2009 J. Chem. Phys. 131 044322 [13] Bryant H C, Mohagheghi A H, Stewart J E, Donahue J B, Quick C R, Reeder R A, Yuan V, Hummer C R, Smith W W, Cohenl S, Reinhardt W P and Overman L 1987 Phys. Rev. Lett. 58 2412 [14] Stewart J E, Bryant H C, Harris P G, Mohagheghi A H, Donahue J B, Quick C R, Reeder R A, Yuan V, Hummer C R, Smith W W and Cohenl S 1988 Phys. Rev. A 38 5628 [15] Du M L 2004 Phys. Rev. A 70 055402