633 nm Laser for Raman Instrument

商业生产的碳纳米管是多种纳米管类型的混合物，其导电性范围从半导体到金属。这种纳米管类型的混合对商业应用是有害的，因为设备需要金属或半导体纳米管的纯样品，这取决于应用。我们的研究工作集中在按类型分离和纯化碳纳米管上，这将使许多应用取得成果。然而，所有纯化纳米管的努力都需要能够在处理过的样品中识别纳米管类型的技术。这种鉴定只能通过光谱测量来实现，这种光谱测量可以区分不同的纳米管类型。一种非常强大的纳米管识别技术是拉曼光谱学，它可以测量激光发出的散射光，并可以确定样品中存在的振动模式。不同类型的纳米管对不同的激光激发波长敏感，为了获得样品组成的完整图像，必须使用多个激光激发波长。633纳米波长是表征纳米管最有用的波长之一，它允许半导体和金属碳纳米管同时激发。只有通过使用这种特定的激发波长，人们才能确定样品中半导体和金属纳米管的相对组成，从而评估分离这些不同纳米管物种的方法。目前，麦克马斯特大学还没有配备633纳米激光源的拉曼仪器。因此，该应用程序要求升级到麦克马斯特现有的功能齐全的拉曼仪器，该仪器将提供633 nm激发样品的能力。许多研究小组迫切需要这种仪器，它将使麦克马斯特大学目前无法进行的许多研究成为可能。

Commercially produced carbon nanotubes are mixtures of multiple nanotube types, which range in conductivity properties from semiconducting to metallic. This mixture of nanotube types is detrimental to commercial applications, as devices require pure samples of either metallic or semiconducting nanotubes, depending on the application. Our research efforts are focused on separating and purifying carbon nanotubes according to type, which will allow many applications to come to fruition. However, all efforts to purify nanotubes require access to techniques that can identify the nanotube types in processed samples. Such identification can only be achieved using spectroscopic measurements that can differentiate between different nanotube types. One extremely powerful technique for nanotube identification is Raman Spectroscopy, which measures scattered light from a laser and allows determination of vibrational modes present within a sample. Different nanotubes types are sensitive to different laser excitation wavelengths, and to get a complete picture of sample composition, one must use multiple laser excitation wavelengths. One of the most useful wavelengths for nanotube characterization is 633 nm, which allows for simultaneous excitation of both semiconducting and metallic carbon nanotubes. It is only by using this specific excitation wavelength that one can determine the relative semiconducting vs. metallic nanotube composition within a sample, allowing the evaluation of methods for separating these different nanotube species. Currently, there is no Raman instrument at McMaster University that is equipped with a 633 nm laser source. This application therefore requests an upgrade to an existing, fully functional Raman instrument at McMaster that will provide the capability to excite samples at 633 nm. This instrument is in dire need by a number of research groups, and will enable numerous studies that are currently impossible at McMaster.