A quantum cascade laser setup for studying irreversible photoreactions in H2O with nanosecond resolution and microlitre consumption.
A quantum cascade laser setup for studying irreversible photoreactions in H2O with nanosecond resolution and microlitre consumption.
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用于研究水中不可逆光反应的量子级联激光器装置，具有纳秒分辨率和微升消耗
DOI：
10.1039/d0cp03164j
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
T. Kottke
中科院分区：
文献类型：
--
作者：
J. L. Klocke;T. Kottke
不可逆反应的时间分辨红外光谱法通常需要进行数千次采集，从而导致高样品消耗。在这里，我们提出了一个装置，采用现代量子级联激光器（QCL）作为探测光源，记录时间分辨的差光谱的不可逆光反应在水。聚焦QCL与耐压流动池和与流动正交的微米级相结合，使我们能够大幅减少样品消耗。我们研究了辅因子黄素单甘肽（FMN）在水中的不可逆光还原，这是生物光感受器中常见的反应。可以使用从20纳秒到1秒的宽时间范围，因为该方法最大限度地减少了流量造成的任何信号漂移。在46个选定的波数下记录动力学，对于完整的数据集消耗12微升。1490-1740 cm−1的调谐范围包括相关的羰基振动和1650 cm−1附近的强吸水区域。通过应用具有Lorentzian总和的拟合来生成光谱维度中的连续数据集。随后的全球分析使我们能够解决参考光谱和动力学的光反应进行从三重激发态通过中间黄素阴离子自由基的产品，完全还原状态的FMN。因此，中性自由基状态在反质子化中不被填充。该方法极大地促进了对含黄素的光感受器和光酶的不可逆反应的光谱访问，具有高时间分辨率和小样品消耗。
Time-resolved infrared spectroscopy on irreversible reactions requires in general an exchange of sample for thousands of acquisitions leading to high sample consumption. Here, we present a setup employing a modern quantum cascade laser (QCL) as a probe light source to record time-resolved difference spectra of irreversible photoreactions in H2O. The combination of the focused QCL with a pressure-tolerant flow cell and a micrometre stage orthogonal to the flow allowed us to drastically reduce the sample consumption. We investigated the irreversible photoreduction of the cofactor flavin mononucleotide (FMN) in H2O, which is a common reaction taking place in biological photoreceptors. A broad time range from 20 nanoseconds to 1 second was accessible, because the approach minimized any signal drift by the flow. Kinetics were recorded at 46 selected wavenumbers consuming 12 microlitres for a complete dataset. The tuning range of 1490–1740 cm−1 included relevant carbonyl vibrations and the region of strong water absorption at around 1650 cm−1. A continuous dataset in the spectral dimension was generated by applying a fit with a sum of Lorentzians. Subsequent global analysis allowed us to resolve reference spectra and kinetics of the photoreaction proceeding from the triplet excited state via the intermediate flavin anion radical to the product, the fully reduced state of FMN. Accordingly, the neutral radical state is not populated in the disproportionation. The approach strongly facilitates the spectroscopic access to irreversible reactions of flavin-containing photoreceptors and photoenzymes with high time resolution and small sample consumption.
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DOI：
10.1039/c3cp43881c
发表时间：
2013
期刊：
Physical chemistry chemical physics : PCCP
影响因子：
--
作者：
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通讯作者：
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