tokens: Two points are indicated : first , the photosensitized damage of YHPD is interrelated to not only 1O2 , but also free radicals ( O2 - . . OH and YHPD - . ) ; second , although the photosensitized damage of YHPD is stronger than that of BHPD , yet the photosensitized damage is negatively correlated to the yield of 1O2 but positively correlated to those of O2 - . and OH .