The photochemistry and photophysics of 2-methyl- (1), 2-(2‘-furylethylidene)- (2), and 2-[(4‘-methoxy)styryl]-4,6-bis(trichloromethyl)-1,3,5-triazine (3), three compounds that find application as photoacid generators in photoresist formulations, have been investigated under conditions of direct excitation and using various phenothiazine derivatives as photosensitizers. C−Cl bond cleavage is confirmed by laser flash photolysis as the primary photochemical step in the direct photolysis of these compounds; the chlorine atoms formed in this reaction can be detected by complexation with chloride anions or benzene. In the case of 1, this photodissociation occurs with a lifetime of <20 ns. The quantum yield of bond breaking for 1 after direct excitation as determined by laser flash photolysis and steady-state irradiations was found to be 30−40 times greater than for 2 and 3. The mechanism under sensitized conditions involves electron transfer from the excited phenothiazines to the triazines as the primary photochemical step; the rate constants for excited-state quenching exceed 10⁹ M^-1 s^-1 for the T₁ state and 10¹⁰ M^-1 s^-1 for the S₁ state. The rate constants correlate with the free energy for electron transfer estimated from the excited-state energies and the oxidation potential of the sensitizers.

中文翻译：

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取代的4,6-双（三氯甲基）-1,3,5-三嗪生成光酸的机理研究

2-甲基-（1），2-（2'-呋喃基亚乙基）-（2）和2-[（（4'-甲氧基）苯乙烯基] -4,6-双（三氯甲基）-1 3,5-triazine（3）是在光致抗蚀剂配方中可用作光酸产生剂的三种化合物，已在直接激发条件下使用各种吩噻嗪衍生物作为光敏剂进行了研究。激光闪光光解证实了C-Cl键的裂解是这些化合物直接光解的主要光化学步骤；该反应中形成的氯原子可通过与氯离子或苯络合来检测。在1的情况下，发生这种光解离的寿命小于20 ns。键断裂的量子产率为通过激光闪光光解法和稳态辐照确定的直接激发后的1，比2和3的大30-40倍。敏化条件下的机理涉及电子从激发的吩噻嗪到三嗪的转移，这是主要的光化学步骤。速率常数的激发态猝灭超过10 ⁹中号^{- 1个}小号^{- 1}于T ₁态和10 ¹⁰中号^{- 1个}小号^{- 1}用于S ₁状态。速率常数与根据激发态能量和敏化剂的氧化势估计的电子转移自由能相关。