TABLE 1.

Relative signal heights/intensities for low-field S₂ state signals at Q-band and X-band

Sample	Cl−	No anion		F−
Q-band signal at g = 4.6
g-factor	4.55	4.62	4.61	4.61
Height/rel. units	100	84.9	70.8	179
Width/G	550–700	400–450	400–450	380–420
Q-band signal at g = 3.1
g-factor	3.16	3.11	3.09	3.08
Height/rel. units	37.4	66.7	88.0	215
Width/G	400–450	400–450	500–550	380–420
X-band signal at g = 4.1
g-factor	4.06	4.13	4.17	4.20
Intensity/rel. units	100	107	106	156
Height/rel. units	100	109	154	215
Width/G	340–370	330–360	290–310	300–315
O2 evolution activity
Relative to Cl−	100	36.1	∼0	10.9

Samples, which correspond to those presented in Fig. 2, were Cl⁻-depleted and subsequently treated with 20 mM sodium salt of the anion indicated. Signal heights were measured from peak to trough; intensities at X-band were also measured by double integration. Each measurement was scaled to account for the number of scans and the sample concentration and normalized to the height of the g = 4.6 signal for the Cl⁻-containing sample at Q-band or the height/intensity of the g = 4.1 signal for the Cl⁻-containing sample at X-band. Measurements at X-band were averaged from two aliquots; measurements at Q-band were from single aliquots of the same samples. Error is estimated to be 10–15% for Q-band signals and 10% for X-band signals. The O₂ evolution activity of the Cl⁻-containing sample was 653 μmolO₂ mgChl⁻¹ h⁻¹.