Development of an Infrared Spectrometer/Scanning Probe Microscope for Materials Characterization at High Spatial Resolution

该项目的目标是构建一个强大的新的研究仪器，用于确定亚微米空间分辨率的材料组成。 新仪器的主要特点将是使用扫描探针显微镜（SPM）来检测材料对傅里叶变换红外光谱仪（FTIR）红外辐射的吸收。 最终，该仪器的空间分辨率有望接近50 nm。 这种空间分辨率至少比红外显微镜好两个数量级，红外显微镜受衍射效应的限制，空间分辨率约等于红外辐射的波长（~ 2.5 - 25 mm）。 由于SPM将被用作红外“探测器”，FTIR和SPM系统的最佳功能将被集成到一个强大的仪器中，该仪器可以提供有关材料表面成分，形貌和性能变化的信息。 将采用两种一般方法。 在一个，SPM将用于测量当样品吸收红外辐射时发生的热膨胀。 来自SPM的信号将被路由到FTIR的外部输入端，其中将执行信号平均和傅立叶变换等功能，以产生样品的红外光谱。 FTIR光谱仪将以步进扫描模式运行，红外辐射将以约100 kHz的频率调制，以限制热扩散长度并提高仪器的空间分辨率。 第二种方法将是类似的，除了SPM将配备一个微型电阻温度计，将用于测量样品的温度增加时，它是用红外辐射照射。 这一新的研究工具将广泛用于有关粘合接头和复合材料界面附近材料的组成、结构和性能的梯度研究，以及有关具有长链和短链双峰分布的弹性体的相分离的研究。 研究计划的一个新方面是通过互联网向远程用户提供FTIR/SPM。

The goal of this project is to construct a powerful new research instrument for determining the composition of materials at sub-micron spatial resolution. The key feature of the new instrument will be the use of a scanning probe microscope (SPM) to detect the absorption by materials of infrared radiation from a Fourier-transform infrared (FTIR) spectrometer. Ultimately, the spatial resolution of this instrument is expected to approach 50 nm. This spatial resolution is at least two orders of magnitude better than that of infrared microscopes that are limited by diffraction effects to a spatial resolution that is approximately equal to the wavelength of infrared radiation (~ 2.5 - 25 mm). Since an SPM will be used as an infrared "detector," the best features of FTIR and SPM systems will be integrated into a single powerful instrument that can provide information about variations in the surface composition, topography, and properties of materials at high spatial resolution. Two general approaches will be employed. In one, the SPM will be used to measure the thermal expansion that occurs when a sample absorbs infrared radiation. Signals from the SPM will be routed to the external input of the FTIR where functions such as signal averaging and Fourier-transformation will be performed to yield the infrared spectrum of the sample. The FTIR spectrometer will be operated in a step-scan mode and the infrared radiation will be modulated at a frequency of about 100 kHz to limit the thermal diffusion length and enhance the spatial resolution of the instrument. The second approach will be similar except that the SPM will be equipped with a miniature resistance thermometer that will be used to measure the increase in temperature of a sample when it is illuminated with infrared radiation. This new research instrument will be used extensively in research concerned with gradients that occur in composition, structure, and properties of materials near interfaces in adhesive joints and composite materials and in research concerned with phase separation in elastomers having a bimodal distribution of long and short chains. A novel aspect of the research plan is to make the FTIR/SPM available to remote users over the Internet.