A broadly tunable quantum cascade laser for spectroscopic characterization

水在稳定生物结构和促进生物功能方面发挥着积极的作用。目前的主要研究方向是确定生物分子在(自然)水环境中的绝对构型。为了实现这一最终目标，建立适当的水溶液中手性分子溶剂化的理论描述是至关重要的。虽然溶液相测量提供了关于溶液中大量分子内和分子间氢键的综合效应的信息，但如果没有在分子水平上详细和准确的实验输入，揭示潜在的机理是极其困难的，如果不是不可能的话。我们解决这一挑战的方法之一是应用喷射冷却高分辨率红外激光光谱来表征几个水分子对手性分子的逐步溶剂化作用。在控制良好的分子束环境中研究这些模型分子系统将使我们能够单独评估各种影响的影响。这种循序渐进的方法对于发展一种新的解的理论描述将是非常有价值的。最近，随着连续波外腔QCL的实现，量子级联激光器(QCL)的发展达到了一个里程碑，它具有宽的频率可调、窄的线宽、优异的输出功率和超模质量。这些关键特性使其成为高分辨率红外激光光谱分析的理想光源。我们将利用这一及时的发展，将这样的QCL应用到我们最近完成的腔增强吸收光谱仪中。需要资金购买一个外腔QCL和一对以6.2微米区域为中心的腔环衰减镜。这是我们对手性分子-(水)_n团簇进行光谱表征所需要的两个基本成分。

Water plays an active role in stabilizing biological structures and facilitating biological functions. Significant current research efforts are directed toward determining absolute configurations of biomolecules in their (natural) aqueous environment. To achieve this ultimate goal, it is essential to develop an adequate theoretical description of solvation of chiral molecules in aqueous solution.While the solution phase measurements provide information on the combined effects of an enormous amount of intra- and intermolecular hydrogen bonding in solution, it is extremely difficult, if not impossible, to uncover the underlying mechanisms without detailed and accurate experimental input on the molecular level. One of our approaches to tackle this challenge is to apply jet-cooled high resolution infrared laser spectroscopy to characterize the stepwise solvation of a chiral molecule by several water molecules. Studies of these model molecular systems in a well controlled molecular beam environment will allow us to assess the influence of various effects separately. Such a stepwise approach will be extremely valuable for developing a new theoretical description of solvation.A monumental milestone was reached recently in quantum cascade laser (QCL) development with the realization of continuous wave external cavity QCLs that have wide frequency tunability, narrow line width, excellent output power, and super mode quality. These key characters make them an ideal laser source for high resolution infrared laser spectroscopy. We will take advantage of this timely development and implement such a QCL into our recently completed cavity enhanced absorption spectrometer. Funds are requested to purchase an external cavity QCl and a pair of cavity ring down mirrors centred at 6.2µm region. These are two essential components that we need for the spectroscopic characterization of the chiral molecule-(water)_n clusters.