Reaction of Oxygen with the Singlet Excited State of [n]Cycloparaphenylenes (n = 9, 12, and 15): A Time-Resolved Transient Absorption Study Seamlessly Covering Time Ranges from Subnanoseconds to Microseconds by the Randomly-Interleaved-Pulse-Train Method
Reaction of Oxygen with the Singlet Excited State of [n]Cycloparaphenylenes (n = 9, 12, and 15): A Time-Resolved Transient Absorption Study Seamlessly Covering Time Ranges from Subnanoseconds to Microseconds by the Randomly-Interleaved-Pulse-Train Method
复制标题
氧气与 [n] 环对亚苯基（n = 9、12 和 15）单线态激发态的反应：时间分辨瞬态吸收研究，通过随机交错脉冲序列方法无缝覆盖从亚纳秒到微秒的时间范围
DOI：
10.1021/acs.jpca.9b09846
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Nakagawa Tatsuo
中科院分区：
文献类型：
--
作者：
Suenobu Tomoyoshi;Arahori Ikuya;Nakayama Ken-ichi;Suzuki Toshiaki;Katoh Ryuzi;Nakagawa Tatsuo
基于本课课组最近开发的随机交错脉冲序列（RIPT）方法，采用亚纳秒到微秒时间范围内的瞬态吸收（TA）测量方法，研究了302与高发光环对苯乙烯（CPPs），即[n]CPP = 9、12和15时的单重态激发态（S1）在溶液中的反应。我们通过观察Sn←s1的瞬态吸收和稳态荧光测量发现s1by3o2的有效猝灭。同时，通过观察到Tn←T1吸收强度的明显增强，我们意识到系统间交叉（ISC）从s1到三态激发态（T1）的速率加快。建立了在无O2条件下ISC的速率常数（kISC0）和3o2条件下仅用TA衰变数据计算ISC的双分子速率常数（kISCO2）的分析方法。在这些分析的基础上，我们进一步成功地确定了T1（ΦT）在有和没有O2的情况下的量子产率。另外，可以参照C60的T1吸收系数估算出T1（εT1）和S1（εS1）的吸收系数。这些光物理参数在很大程度上取决于环的大小，其中S1的寿命（τS）在o2的存在和不存在下占主导地位ΦTas以及荧光的量子产率（ΦF）。
Reaction of3O2with singlet excited state (S1) of highly luminescent cycloparaphenylenes (CPPs), i.e., [n]CPP wheren= 9, 12, and 15 in solution has been studied by transient absorption (TA) measurements seamless for the time range from subnanosecond to microsecond based on the randomly-interleaved-pulse-train (RIPT) method recently developed by our group. We found efficient quenching of S1by3O2through observation of Sn← S1transient absorption and the steady state fluorescence measurements. Concomitantly, we have become aware of the acceleration of the rate of intersystem crossing (ISC) from S1to the triplet excited state (T1) through the observation of the evident enhancement of Tn← T1absorption intensity. We have established the analysis procedure to evaluate the rate constant of ISC (kISC0) in the absence of O2and the bimolecular rate constant of ISC induced by3O2(kISCO2) only by using TA decay data in the presence of O2. On the basis of these analyses, we further succeeded in determining the quantum yield of T1(ΦT) with and without O2. In addition, the absorption coefficient of T1(εT1) and S1(εS1) could be estimated with reference to that of T1of C60. These photophysical parameters are largely dependent on the ring size, where the lifetime of S1(τS) in the absence and presence of O2dominates ΦTas well as the quantum yield of fluorescence (ΦF).