10146 J. Phys. Chem. B, Vol. 105, No. 41, 2001
ADDITIONS AND CORRECTIONS 1999, Volume 103B R. J. Hulsebosch, I. V. Borovykh, S. V. Paschenko, P. Gast, and A. J. Hoff*: Radical Pair Dynamics and Interactions in Quinone-Reconstituted Photosynthetic Reaction Centers of Rb. Sphaeroides R26: A Multifrequency Magnetic Resonance Study Page 6815. Due to a sign mistake in our simulation program, we determined incorrectly the sign of JPΦ, the exchange interaction between P+• and ΦA-•. With the corrected program, we obtain virtually identical simulations as published with all parameters left as they were 1, with the exception of the sign of JPΦ, which is changed to positiVe. The conclusion that the sign of JPΦ is positive is supported by the following simple qualitative argument. With kQ diminishing relative to kS and kT, the cancellation in the 12-34 and 13-24 doublets (Scheme 11) becomes less effective and the way the polarization pattern of the radical pair spectrum changes is determined by the sign(I12 + I34): the spectrum evolves toward pure EA pattern for positive I12 + I34 and toward pure AE pattern for negative I12 + I34. (Here, EA denotes emissive polarization for a radical that resonates in lower magnetic field, and absorptive polarization for a radical that resonates in higher magnetic field.) Using notation and eqs 23 and 24 from 2, we can show that in our case, sign(I12 + I34) is determined by sign(JPΦ) at D-band
sign(I12+I34) ) -sign(I13+I24) ) sign(j1)sign(Q1)sign(Q2) ) sign(j1) ) sign(JPΦ), since (a) at D-band, |j2| , |Q2| (leading to c ≈ 0, s ≈ sign(Q2)‚1), (b) sign(Q1)sign(Q2) ) + for the vast majority of orientations (because at D-band, Q1 and Q2 are determined mainly by orientation-dependent g-factors, and for the vast majority of orientations gQ(θ,φ) > gP(θ,φ) and gΦ(θ,φ) > gP(θ,φ)), and (c) the sign of j1 ) JPΦ + 0.5 DPΦ(cos2ξ1 - 1/3) is determined by the sign of JPΦ for values of DPΦ of about -0.5 mT, and |JPΦ| in the range of 0.5 to 1 mT. (The validity of these values was discussed by us in ref 1.) From the D-band experimental spectra of P+•QA-• we see that upon going from fast to slow kQ (from UQ- to DQ- to AQ-RCs), the polarization pattern becomes more and more like pure EA (Figure 21), so we conclude that JPΦ is positive. Notice that our results now correspond well to the work of Tang et al. 3, who used a value of JPΦ ) +7 G for their simulations. We are indebted to Dr. P. J. Hore for fruitful discussions. References and Notes (1) Hulsebosch, R. J.; Borovykh, I. V.; Paschenko, S. V.; Gast, P.; Hoff, A. J. J. Phys. Chem. B 1999, 103, 6815. (2) Hore, P. J. Mol. Phys. 1996, 89, 1195. (3) Tang, X. S.; Zheng, M.; Chisholm, D. A.; Dismukes, G. C.; Diner, B. A. Biochemistry 1996, 35, 1475.
10.1021/jp012272+ Published on Web 09/22/2001
