Cuvettes, optical quartz

Measuring cuvettes, in which sample solutions are placed, are made of various materials depending on the range of radiation used in the measurement. Measurements in the UV are performed with the use of quartz cuvettes. Synthetic quartz, which is less contaminated with traces of metals, has better optical properties. Measurements in the VIS range are made using quartz, glass, or plastic cuvettes. 

All the absorption spectra in the 190-1100 nm range were recorded at room temperature on solutions contained in quartz cuvettes (optical pathlength 1 and 5 cm, Helhna ) by using a Perkin Elmer 140 spectrophotometer. The precision on the wavelength values was 2 nm. Molar absorption coeflhcient values were determined using the Lambert-Beer law the experimental error, mostly due to weighting error, can be estimated to be around 5%. 

What material is the sample tube made of Just like a cuvette in a UV-visible spectrometer has to be optically transparent, the EPR sample tube must be transparent for the magnetic component of microwaves. High-quality quartz is the preferred construction material low-quality quartz and especially any type of glass will not... 

The absorbance spectrum of a liquid or solution can be readily measured by using quartz or sapphire cuvettes and fiber-optic probes of variable path lengths. The most suitable solvents for this purpose are those not containing 0-H, N-H and C-H groups which exhibit little or no absorption in this spectral region, such as CHCI3, CCI4 or CS2. 

Optical Applications. Vitreous silica is ideal for many optical applications because of its excellent ultraviolet transmission, resistance to radiation darkening, optical polishing properties, and physical and chemical stability. It is used for prisms, lenses, cells, windows, and other optical components where ultraviolet transmission is critical. Cuvettes used in scatter and spectrophotometer cells are manufactured from fused silica and fused quartz because of the transmissive properties and high purity (222). 

Figure 17.11 Transmission spectroelectrochemistry cell designed for use with room-temperature haloaluminate melts and other moisture-reactive, corrosive liquids, (a) Auxiliary electrode and reference electrode compartments, (b) quartz cuvette containing the RVC-OTE, (c) brass clamping screw, (d) passageway between the separator and OTE compartment, (e) fritted glass separator, (f) A1 plate, (g) lower cell body (Teflon), (h) upper cell body (Teflon). This cell is normally used inside a glove box and is optically accessed with fiber optic waveguides. [From E. H. Ward and C. L. Hussey, Anal. Chem. 59 213 (1987), with permission.]...

Regarding the UV assay, excessive absorption may be encountered in certain cases. For example, the Good buffers PIPES and HEPES absorb substantially at 234 nm. The optional use of a 9-mm optically transparent quartz spacer inserted into a 1-cm cuvette gives a 10-fold advantage with solutions of high UV absorbance. The spacer also serves as a convenient mixer, whereas mixing is difficult with specialized 1-mm cuvettes. 

The femtosecond transient absorption studies were performed with 387 nm laser pulses (1 khz, 150 fs pulse width) from an amplified Ti Sapphire laser system (Model CPA 2101, Clark-MXR Inc). A NOPA optical parametric converter was used to generate ultrashort tunable visible pulses from the pump pulses. The apparatus is referred to as a two-beam setup, where the pump pulse is used as excitation source for transient species and the delay of the probe pulse is exactly controlled by an optical delay rail. As probe (white light continuum), a small fraction of pulses stemming from the CPA laser system was focused by a 50 mm lens into a 2-mm thick sapphire disc. A schematic representation of the setup is given below in Fig. 7.2. 2.0 mm quartz cuvettes were used for all measurements. 

The assay method of Dalziel is convenient. In a recording ultraviolet spectrophotometer set at 340 nm is placed a 3-mL quartz cuvette containing 2.4 mL of 0.10 M glycine-sodium hydroxide buffer solution, pH 9, 500 pL of a 54 mM solution of ethanol 1n the same buffer, and 100 pL of a 15 nM solution of NAD, also in the same pH 9 buffer. The volume is made up to 3.0 mL, and the assay initiated by the addition of 10 pL of a 1 mg per mL solution of HLADH in 0.10 M "Tris-hydrochloric acid buffer", pH 7.4. The change in optical density at 340 nm 1s monitored at 25°C and the activity calculated from the following equation ... 

Weckhuysen and coworkers (Mesu et al., 2005 Tinnemans et al., 2006) also presented a combination of UV-vis (fiber optics) and XAFS (energy dispersive) spectroscopy for the analysis of homogeneous liquid-phase reactions. Both methods are performed in transmission, with the beams crossing in a cuvette (5-mm path length each) with quartz windows. 

As a result, cuvettes for Raman spectroscopy should be carefully selected. They may, due to their impurities, add a background to the spectrum of the sample. In addition, all cuvette materials produce their own Raman spectra, which have to be considered, when the Raman spectra of the sample are evaluated. Fig. 3.5-17 a shows a Raman spectrum of a typical optical glass BK7, Fig. 3.5-17 b that of quartz glass suprasil, and Fig. 3.5-17 c of sapphire. Suprasil is a synthetic quartz which does not normally contain impurities. Therefore, Suprasil of ESR quality is highly recommended as Raman cuvette material. Also, sapphire is a good cuvette material, as it is very hard, inert, has a good thermal conductance, and shows only weak but sharp Raman lines (Porto and Krishnan, 1967). It is used for the production of the universal Raman cell (Schrader, 1987). The sharp Raman lines of sapphire observed in the spectra of the sample may be subtracted from the spectrum or used as internal standard for quantitative analyses (Mattioli et al, 1991). 

The irradiation system consisted of an Optical Module X (model SX-UI500 MQQ) and a power supply unit (model BA-H500) (360 nm cutoff, 70-450 mW/cm, and the distances between the collimator lens and the quartz cuvette were 40-160 cm) was obtained from USIO Electronics (Tokyo, Japan). The light power meter was purchased from Advantest (Tokyo, Japan). A Lumat LB 9501 (Berthold, Wildbad, Germany) was used to measure the CL with a round-bottom glass tube (75 x 12 mm... 

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