Spectroscopy in Transmission

Transcription

1 Spectroscopy in Transmission + Reflectance UV/VIS - NIR Absorption spectra of solids and liquids can be measured with the desktop spectrograph Lambda 9. Extinctions up to in a wavelength range from UV up to long wave NIR can be detected. A integrating sphere can be integrated in the spectrometer to measure specular and diffuse reflectance as well as transmission. FT- MIR / NIR Spectroscopy IR spectra are being measured with an Perkin Elmer System 000 FTIR spectrometer. The sample can be measured in transmission, diffuse reflectance or in ATR mode. Fluorescence Spectroscopy The Fluorolog Spex spectrometer provides fluorescence measurements in a wavelength range from 00 to 700 nm. The emission spectra can be recorded from 300 until 000 nm with a signal to noise ratio to 000:. This system allows measurement of 3D spectra by successively scanning through the excitation wavelengths. Raman Spectroscopy The Kaiser Optics Raman system can be applied for inline measurements to analyse and monitor chemical processes. In addition solids, powders, gels and liquids can be measured online with different probes. Probe Technologies Various probes can be attached to spectrometers with fibre optics for inline/online process measurements. Concerning this matter we provide solutions for the measurement in transmission, diffuse reflection, attenuated total reflectance (ATR), transflection and Raman scattering. Alteburgstraße 50, 776 Reutlingen Tel. / Fax ++9 (0) 7 / 7 00 / 03

2 In Situ Monitoring of Chemical and Biochemical Reactions Biochemical-reactor A laboratory-scale chemical reactor, a bioreactor and a pressurised vessel are available for in situ measurements of all kinds of chemical or biochemical reactions. In situ spectroscopy is performed in transmission, attenuated total reflection (ATR) or scatter mode for UV/ VIS, NIR and IR range, ultrasonic measurements and Raman analysis. Reaction parameters (e. g. ph, temperature, viscosity, foaming) and the dosing of reagents are monitored and controlled via computer. The apparatus is complemented by a HPLC system. The following probes are used: Transmission tunnel cell with scattering port (for stray light and fluorescence). Transmission probes. ATR tunnel cell. ATR immersion probes (UV / Vis and IR). Immersion probe that combines transmission UV/ Vis NIR spectroscopy with IR in ATR mode. Raman immersion probe. Ultrasonic and Zeta-Potential probe. On-line probes that measure the mean particle size, the size distribution and the concentration. Chemical-reactor Incident ATR Tunnel Cell In Out Reflected Transmission Immersion Cell Input ATR Immersion Cell Incident Raman Immersion Probe Excitation Collection (Laser) (Scattering) Fiber Size 90 µm Fiber Size 00 µm ATR Crystal Transmission Flow Cell Input In Transmission Reflected Long- Pass Filter Band- Pass Filter Out Scatter Port Solution ATR Crystal Solution Dichroic Mirror Micro-reactor Alteburgstraße 50, 776 Reutlingen Tel. / Fax ++9 (0) 7 / 7 00 / 03

3 On-Line Monitoring of Solids, Surfaces and Biological Materials methods and spectroscopic sensors are well suited for the on-line quality control. They are fast and measure non-invasively and non-destructively. An on-line instrument for that purpose implements the insight that is acquired in the previous steps and that determines the properties of the system, e. g. the optimum measuring range, the best suited optics and spectroscopic devices. Additionally, the on-line system has to meet industrial requirements and must work efficiently even under harsh conditions at the production line. Besides the cost factor, a reliable and user-friendly maintenance is important. The main requirements include a long time stability and high robustness of the system. Fluctuations of the light source, Flutter effects (i. e. a rising or falling surface, measuring out of focus) as well as optical density fluctuations, e. g. on the fast moving conveyor belt, have to be compensated. A smart control software ensures the operativeness, performs calibrations automatically and aligns the system with internal reference standards. The prototype is developed in close co-operation with the industry. Based on a modular construction, it is optimised for one particular measuring task and, hence, will always be a specific and unique solution. The on-line control system is complemented by a highlevel multivariate data analysis including appropriate calibration models. On-Line Control of Wood Chips Alteburgstraße 50, 776 Reutlingen Tel. / Fax ++9 (0) 7 / 7 00 / 03

4 PC c b c c c c b b c c c c c b b b b b b b b c c c c c b b b b b b b b b c c c c c c c c b b b b b b b b b b b b b b b b c c c c c c c c c c c c c c c c c c b b b c c c b c c b c c c c c c c c c c c c b b b b b b b b b c b b b b b b b b b c c c c c c c c c c c c c b b b c c c c c c b b b b b c c c c c c c c c c c c b PC RESULT6, X-expl: 9%,6% Scores RESULT7, PC(X-expl): (98%) Scores s Redundant Useful Data Analysis No Non- Specific Chemometrics and Biometrics After the collection of the spectroscopic data, different strategies are applied to extract the most important and fundamental information from a large set of data. Experimental design is used to select or design the sample and data set. The recorded data are illustrated, evaluated, summarised and reviewed carefully. Based on a recognised pattern, a calibration model is calculated and tested, i. e. applied to another set of samples. If this test gives reasonable results, the model is verified and, finally, will be generalised to meet the requirements in the real world at the production line. Additionally, this fundamental model serves as guideline for the design and construction of a monitoring system for on-line or in situ process control Process Analysis Tools Correlation and regression methods Unscrambler, Design Expert, SPSS, SIMCA Time series, data visualisation MatLab Toolbox, PLS - Toolbox c c c c b b b b b b b c cc c c cc c c b c bb b c c c c c c c c c c bb b b b b b b b c b c b b b b b b Analysis, Modelling and Simulation (Selection) Principal Component Analysis (PCA) Partial Least Square Regression (PLS) Multivariate Curve Resolution (MCR) Neuronal Networks (Kohonen, RBF) Clustering (hierarchical, K-mean) Evolving Factor Analysis (EFA) and Multivariate Curve Resolution (MCR) EFA and MCR are procedures that calculate the number of relevant chemical compounds and their concentration, respectively, directly from the reaction spectra. Alteburgstraße 50, 776 Reutlingen Tel. / Fax ++9 (0) 7 / 7 00 / 03

5 Complementary Research Toolbox Ultrasonic Spectroscopy and Travel Time Measurement Ultrasonic spectroscopy measures specific properties, e. g. density, particle size, concentration and viscosity, even of colloidal suspensions. According to the ultrasonic frequency and the sample properties (attenuation, absorption of ultrasonic waves), the resonator method or the pulse modulated travelling method is used. Additionally, the zeta potential of particles in a liquid can be measured on-line. Dielectric Spectroscopy Dielectric analysis permits fully automated measurement of dielectric material constants over a wide frequency range. In addition, volume and surface resistivity can be determined on the same sample. Dielectric Constants Volume and Surface Resistivity Corrosion Electrochemistry / Impedance Impedance spectroscopy is used in combination with optical methods to investigate electrochemical processes on interfaces, for example corrosion. With cyclic voltammetry the electrochemically reactive compounds of a liquid are analysed. Cyclic voltammetry is also combined with optical methods. Cyclic Voltammetry U Frequency Response Analyser I Z = U / I Potentiostat BE RE WE Measuring Cell BE... backing electrode RE... reference electrode WE... working electrode Alteburgstraße 50, 776 Reutlingen Tel. / Fax ++9 (0) 7 / 7 00 / 03