Micro spectrometer

CO Resistive sensors pellistors, metal-oxide sensors Optical sensors micro-spectrometer, IR-sources, IR-detectors, IR-filters Hybrid or integrated, surface micromachining Sn02 sintered thick film (Figaro, FIS,. ..), Sn02 thin and thick film on silicon (MiCS, Microsens) IR spectroscopy (Vaisala, Honeywell,. ..)... 

VOC (volatile organic compound Work-function sensors, micro-spectrometer, IR-sources, IR-detectors, I R-filters Hybrid or integrated, surface micromachining... 

Tsukahara, Y., Ohira, K Saito, M and Briggs, G. A. D. (1989b). Evaluation of polymer coatings by ultrasonic spectroscopy. In Acoustical imaging, Vol. 17 (ed. H. Shimizu, N. Chubachi, and J. Kushibiki), pp. 257-64. Plenum Press, New York. [214] Tsukahara, Y., Ohira, K., and Nakaso, N. (1990). An ultrasonic micro-spectrometer for the evaluation of elastic properties with microscopic resolution. IEEE 1990 Ultrasonics Symposium, pp. 925-30 [149]... 

Figure 4.71 Micro spectrometer (2000-14 000 nm) for inline mid-infrared measurements [119]...

The visible to near-infrared spectral region (375-740 or 680-1080 nm, resolution < 10 nm) is the domain of a micro spectrometer presented by the Institut fur Mikrotechnik Mainz [121]. This device (overall dimensions 16 x 28 x 38 mm) is commercially available but not yet adapted to direct inline measurements in a plant (Figure 4.72). 

Adams, M.L., Enzelberger, M., Quake, S., Scherer, A., Microfluidic integration on detector arrays for absorption and fluorescence micro-spectrometers Sensors... 

For IR measurements of the film samples upon cooling, the above cooling system is placed on the sample stage of the IR micro-spectrometer (Jasco FT/IR-620 Plus + IRT30). 

Another detector selected for its compactness and its orthogonality with respect to GC and MS, is spectro-chemical or optical emission as generated, e.g., by micro discharge detectors (MDD). Figure 9.3.6 presents photos of such emission for both in CO2 and in He (at left) and a cross section on an envisioned MDD structure, coupled into a linear-filter-based micro-spectrometer, which is compact but not efficient. 

D. Brennan, J. Alderman, L. Sattler, B. O Connor, C. O Mathuna. Issues in development of NIR micro spectrometer system for on-line process monitoring of milk product. Measurement, 33(1) 67-74, 2003. 

An optimized evanescent wave micro sensor allows the integration into a spectroscopic micro system for chemical analysis, by combining it with a miniaturized incandescent light source, an NIR micro spectrometer and a diode array detector. A concept of this set-up is shown in fig. 14 [13]. A miniaturized incandescent light source, which provides a continuous emission... 

Characterization methods. The 100 kV Vacuum Generator HB-5 STEM was used to mlcroanalyze samples. The HB-5 has a KEVEX SI(LI) energy dispersive X-ray spectrometer (EDS) and micro area electron diffraction (MAED) capabilities In conjunction with simultaneous bright and dark field Imaging capabilities. A more detailed explanation of the Instrumental operation can be obtained In a publication by C. Lyman(12). 

Specific surface areas of the catalysts used were determined by nitrogen adsorption (77.4 K) employing BET method via Sorptomatic 1900 (Carlo-Erba). X-ray difiraction (XRD) patterns of powdered catalysts were carried out on a Siemens D500 (0 / 20) dififactometer with Cu K monochromatic radiation. For the temperature-programmed desorption (TPD) experiments the catalyst (0.3 g) was pre-treated at diflferent temperatures (100-700 °C) under helium flow (5-20 Nml min ) in a micro-catalytic tubular reactor for 3 hours. The treated sample was exposed to methanol vapor (0.01-0.10 kPa) for 2 hours at 260 °C. The system was cooled at room temperature under helium for 30 minutes and then heated at the rate of 4 °C min . Effluents were continuously analyzed using a quadruple mass spectrometer (type QMG420, Balzers AG). 

Processing in the micro reactor was analyzed by a CCD camera with a long working distance magnifying lens [22]. Visible spectrometry was applied for in-line sensing. The change in product concentration was determined at 450 nm. The light was collected via an optical fiber and sent to the spectrometer. 

In Raman measurements [57], the 514-nm line of an Ar+ laser, the 325-nm line of a He-Cd laser, and the 244-nm line of an intracavity frequency-doubled Ar+ laser were employed. The incident laser beam was directed onto the sample surface under the back-scattering geometry, and the samples were kept at room temperature. In the 514-nm excitation, the scattered light was collected and dispersed in a SPEX 1403 double monochromator and detected with a photomultiplier. The laser output power was 300 mW. In the 325- and 244-nm excitations, the scattered light was collected with fused silica optics and was analyzed with a UV-enhanced CCD camera, using a Renishaw micro-Raman system 1000 spectrometer modified for use at 325 and 244 nm, respectively. A laser output of 10 mW was used, which resulted in an incident power at the sample of approximately 1.5 mW. The spectral resolution was approximately 2 cm k That no photoalteration of the samples occurred during the UV laser irradiation was ensured by confirming that the visible Raman spectra were unaltered after the UV Raman measurements. 

Mass spectrometers must be regularly tuned or calibrated against a known standard, e.g. perfluorotributy-lamine (PFTBA). The trend is towards miniaturisation (10 x 24 x 14 in.). A concept for a micro mass spectrometer, with potential applications in process monitoring, has been presented [167]. Mass-spectrometry instrumentation (1997) has been reviewed [166]. 

The ionspray (ISP, or pneumatically assisted electrospray) LC-MS interface offers all the benefits of electrospray ionisation with the additional advantages of accommodating a wide liquid flow range (up to 1 rnl.rnin ) and improved ion current stability [536]. In most LC-MS applications, one aims at introducing the highest possible flow-rate to the interface. While early ESI interfaces show best performance at 5-l() iLrnin, ion-spray interfaces are optimised for flow-rates between 50 and 200 xLmin 1. A gradient capillary HPLC system (320 xm i.d., 3-5 xLmin 1) is ideally suited for direct coupling to an electrospray mass spectrometer [537]. In sample-limited cases, nano-ISP interfaces are applied which can efficiently be operated at sub-p,Lmin 1 flow-rates [538,539]. These flow-rates are directly compatible with micro- and capillary HPLC systems, and with other separation techniques (CE, CEC). 

Figure 3.7. Schematic diagram of the basic layout of the apparatus typically employed in micro-Raman spectrometers, or microprobes. (From Turrell and Corset 1996.)...

EPR spectrometers use radiation in the giga-hertz range (GHz is 109 Hz), and the most common type of spectrometer operates with radiation in the X-band of micro-waves (i.e., a frequency of circa 9-10 GHz). For a resonance frequency of 9.500 GHz (9500 MHz), and a g-value of 2.00232, the resonance field is 0.338987 tesla. The value ge = 2.00232 is a theoretical one calculated for a free unpaired electron in vacuo. Although this esoteric entity may perhaps not strike us as being of high (bio) chemical relevance, it is in fact the reference system of EPR spectroscopy, and thus of comparable importance as the chemical-shift position of the II line of tetra-methylsilane in NMR spectroscopy, or the reduction potential of the normal hydrogen electrode in electrochemistry. 

In the mid-IR, routine infrared spectroscopy nowadays almost exclusively uses Fourier-transform (FT) spectrometers. This principle is a standard method in modem analytical chemistry45. Although some efforts have been made to design ultra-compact FT-IR spectrometers for use under real-world conditions, standard systems are still too bulky for many applications. A new approach is the use of micro-fabrication techniques. As an example for this technology, a miniature single-pass Fourier transform spectrometer integrated on a 10 x 5 cm optical bench has been demonstrated to be feasible. Based upon a classical Michelson interferometer design, all... 

The design of the mass spectrometer may influence its use in a particular kind of measurement. The study of electronic state-specific ions and their reactions has mainly been carried out using the GIB method. Metastable ions (ions produced by the ionization process but decomposing on the way to detection) can be observed in many of Type (1) mass spectrometers and metastable ions aid our understanding of the ionization process and stability of ions. Sequential reactions and kinetic studies of ion-molecule reactions are difficult with the simpler mass spectrometers of Type 1 and so more complex hybrid mass spectrometers have to be used. The ions observed in micro- or milliseconds after the ionization process may or may not be the same as ion observed seconds after the ionization process, which is a limitation in the use of Type 1 mass spectrometers. 

Bronk, H., Rohrs, S., Bjeoumikhov, N., et al. (2001). ArtTAX- a new mobile spectrometer for energy-dispersive micro X-ray fluorescence spectrometry on art and archaeological objects. Fresenius Journal of Analytical Chemistry 371 307-316. 

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