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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Probing Confined Water with Nonphotochemical Hole Burning Spectroscopy: Aluminum Phthalocyanine Tetrasulfonate in Poly(2-hydroxyethyl methacrylate)
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Probing Confined Water with Nonphotochemical Hole Burning Spectroscopy: Aluminum Phthalocyanine Tetrasulfonate in Poly(2-hydroxyethyl methacrylate)

机译：用非光化学空穴燃烧光谱探测承压水：聚甲基丙烯酸2-羟乙酯中的酞菁铝四磺酸盐

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Nonphotochemical hole burning is used to measure the linear electron-phonon coupling, the temperature dependence of the pure dephasing, and the zero-phonon hole growth kinetics of aluminum phthalocyanine tetrasulfonate (APT) in glassy water confined in pores (～30 A) of films of poly(2-hydroxyethyl methacrylate) (poly-HEMA). The hole burning properties of APT in the polymer are compared with those of APT in hyperquenched glassy films of water and ethanol. Below ～8 K in the polymer, the dephasing, which is dominated by coupling to the intrinsic two-level systems (TLS_(int)) of the glass, is found to be more similar to that of APT in unannealed hyperquenched glassy water (HGW) films than in annealed HGW films. This shows, for the first time, that confinement does not lead to a significant decrease in the TLS_(int) density. At higher temperatures, dephasing due to exchange coupling with a pseudolocalized mode at 42 cm~(-1) becomes dominant. This coupling is due to diagonal quadratic electron-phonon coupling that lead to a change in mode energy upon electronic excitation of APT. The 42 cm~(-1) vibration is assigned to the transverse acoustic mode of confined water. In HGW the energy of this mode is 50 cm~(-1). The interaction of APT with surface-bound water and the polymer surface also leads to reduction of the energy of the linearly coupled (Franck-Condon active) phonon mode from 38 cm~(-1) for HGW to 32 cm~(-1). Hole growth kinetics measurements for APT in polymer saturated with D_2O are compared with those in polymer saturated with H_2O. In the heavy water the hole burning is 330 times slower. The equivalent factor for heavy HGW is 800. Thus, the mechanism of hole burning involves proton tunneling associated with the extrinsic two-level systems (TLS_(ext)) introduced by the dye. In contrast, dephasing data indicate that the coordinate of the TLS_(int) is spatially extended and involves only small-amplitude motion of protons. Differences between the hole-burning properties of APT in poly-HEMA and in HGW and hyperquenched ethanol are discussed in terms of the interactions of APT with bound (nonfreezable) water and the hydroxyethyl groups of the polymer.
机译：非光化学空穴燃烧用于测量膜孔（〜30 A）中的玻璃态水中铝酞菁四磺酸铝（APT）的线性电子-声子耦合，纯相移的温度依赖性以及零声子空穴生长动力学。聚（甲基丙烯酸2-羟乙酯）（聚-HEMA）。将聚合物中APT的空穴燃烧性能与在水和乙醇的超淬火玻璃状薄膜中的APT进行比较。在聚合物中约8 K以下，相变主要通过耦合到玻璃的固有两级体系（TLS_（int））来进行，发现与未经退火的超淬火玻璃水（HGW）中的APT相似。 ）薄膜，而不是退火的HGW薄膜。这首次表明，限制不会导致TLS_（int）密度显着降低。在较高的温度下，由于在42 cm〜（-1）处的伪局部模式与交换耦合引起的相移变得占主导。这种耦合是由于对角二次电子-声子耦合引起的，该对角二次电子-声子耦合在APT电子激发时导致模式能量发生变化。 42 cm〜（-1）的振动被分配给承压水的横向声模。在HGW中，此模式的能量为50 cm〜（-1）。 APT与表面结合水和聚合物表面的相互作用还导致线性耦合（弗朗克-康登活性）声子模式的能量从HGW的38 cm〜（-1）降低到32 cm〜（-1） 。将在D_2O饱和的聚合物中APT的空穴生长动力学测量结果与在H_2O饱和的聚合物中的APT进行了比较。在重水中，燃烧洞的速度要慢330倍。重HGW的等效因子为800。因此，空穴燃烧的机制涉及与染料引入的外在两级系统（TLS_（ext））相关的质子隧穿。相反，移相数据表明TLS_（int）的坐标在空间上扩展并且仅涉及质子的小幅度运动。根据APT与结合的（不可冻结的）水和聚合物的羟乙基之间的相互作用，讨论了聚HEMA和HGW和超淬火乙醇中APT的空穴燃烧性能之间的差异。

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