ULTRAFAST TIME RESOLVED LAUE DIFFRACTION ON DI-RHODIUM COMPLEXES

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 本实验旨在为研究分子单晶中的光激发过程提供实验数据。最初的光激发过程发生在极短的时间尺度上(飞秒/皮秒时间域)，并因其可能的应用而成为科学研究的焦点，例如作为光开关。光激发后，在一个单晶中可以形成几种物种，其中一些物种的寿命长达几毫秒。我们提出了在不同激光强度下对金属配体分子晶体进行光激发后的时间分辨劳厄衍射。这些化合物在光生电子自旋反转三重态中具有特殊的特征。这种机制的一个直接应用是在光学发光二极管的功能设计中。所提出的在不同温度下进行的实验将为光诱导结构机制提供额外的内部信息。这应该提供关于晶体中光激发物种布居和衰变机制的结构动力学信息，澄清可以积极用于发光应用的热传递和结构状态布居的基本问题。作为样品，我们选择了Rh2(1，8-diisocyano-p-menthane)4(PF6)2&#903；CH3CN(Rh-DIMEN)，这是一种已知在单晶中产生激发态的化合物，在从15K到室温的100 ns-？S时间尺度内具有不同的寿命。在微秒时间分辨率的实验中，1.9%(532 nm激发)和2.5%(355 Nm)的激发态布居已经被修正。从超快光学实验(内部研究)，我们预计在400 nm激发，100fs激光脉冲时，光活性三重态的布居数高达5%。我们建议首先研究晶体对更高激光强度的响应，然后进行随温度变化的测量。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The experiment aims at providing experimental data for an investigation of photo-excitation processes in molecular single-crystals. The initial photo-excitation processes occur on extremely short time-scales (femto-/picosecond time domain) and have been in the focus of scientific investigations due to their possible applications, e.g. as optical switches. Following optical excitation several species can be formed in a single crystal, some of which live up to some milliseconds. We propose to carry out time-resolved Laue diffraction following photo-excitation for varying laser intensities on metal-ligand molecular crystals. These compounds have extraordinary characteristics in photo-producing electron-spin flipped triplet states. One direct application of this mechanism is built in the functional design of optical light emitting diodes. The proposed experiments carried out at different temperatures will give an additional inside into the photo-induced structural mechanism. This should provide information about the structural dynamics underlying the population and decay mechanism of the photoexcited species in crystals clarifying fundamental questions of heat transfer and population of structural states which can actively be used for light-emitting application. As sample we have selected Rh2(1,8-diisocyano-p-menthane)4(PF6)2·CH3CN (Rh-dimen), a compound that is known to produce exited states in the single crystal with varying lifetimes in the 100 ns-¿s timescales at temperatures from 15 K to room temperature. Excited state populations of 1.9% (532 nm excitation) and 2.5% (355 nm) have already been refined in experiments with microsecond time resolution. From ultrafast optical experiments (in house research) we expect populations of the light-active triplet state of up to 5% for 400 nm excitation with 100 fs laser pulses.We propose to first investigate in the response of the crystal to higher laser intensities and then carry out temperature dependent measurements.