Double-beam configuration

The most common separators include the Ryhage or jet diffusion separator (74), the Watson-Biemann or pore diffusion separator (75), and the membrane solution diffusion separator originally developed by Llewellyn (75). The first two separators involve direct passage of the sample into the mass spectrometer the low molecular weight helium diffuses more readily and is pumped away. The membrane separator involves diffusion of the sample through a silicone membrane while the carrier gas vents to the atmosphere carrier gas is thus not confined to helium. There is no best separator the choice depends on the nature of the compounds, the temperature range over which it will be operated, and most usually what is available in a particular laboratory. A convenient configuration for a double-beam mass spectrometer such as the AEI MS-30 is two different separators, one into each beam, which permits rapid evaluation of separator performance. 

Instruments with double monochromator configurations, or equivalent multi-pass configurations, can greatly reduce stray light (which is any radiation of wavelength other than that of the columnated light beam). Absorbance in the presence of stray light can be expressed as ... 

Figure 1.6 Configurations of instruments for atomic absorption spectrometry, (a) Single-beam spectrometer (b) double-beam spectrometer.

Fig. 3. Schematic diagram of the guided ion beam tandem mass spectrometer, double octopole configuration. Pumping speeds are shown. Ion sources available are listed and the microwave discharge source is shown. Adapted from [9]...

Figure 4.6-12 Schematic representation of the experiment for recording the optical rotation of the sample S P vector of polarizer, i.c. direction of the electric vector of transmitted radiation, A vector of analyzer the sample rotates the electric vector of the radiation through an angle g leading (as indicated by the broken lines) to different intensities in the two experimental configurations to be realized readily with a double-beam spectrometer or sequentially with a single-beam in.strument.

EBIT as shown in Fig. 2. The trapped Si + ions will lie at the laser beam waist within the enhancement cavity, and to keep the finesse of the cavity as high as possible it is necessary for the high reflectivity mirrors to lie within the EBIT vacnnm chamber. The Ti sapphire laser will be locked to the high finesse cavity nsing the rf sideband locking techniqne [33]. Fast frequency fluctuations will be corrected using an acousto-optic modulator in a double-pass configuration, whilst the slower branch of the servo loop will use a piezo-mounted mirror in the laser cavity. 

Standard Mode I Double Cantilever Beam specimens for delamination testing of a unidirectional (UD) IM7/977-2 composite were Z-pinned with two separate blocks of Z-Fiber reinforcement. The reinforced beam configuration was such as to provoke an unstable delamination, propagating between the two Z-pin blocks. Crack resistance curves for these specific geometry specimens of IM7/977-2 indicate that the unstable delamination cracks are arrested by the second Z-pin block, with the crack propagation resistance being dictated primarily by the Z-pinning density within a block. Acoustic emission analysis is used to interpret visual observations and other test data. 

With single-beam designs, the array dark current is measured and stored in conipulcr memory. Next, the specirum of the source is obtained and stored in memory after dark-current subtraction. Finally, the raw spectrum of the sample is obtained and. after dark-current subtraction, the sample values are divided by the source values at each wavelength to give absorbances. Multichannel instruments can also be configured as double-beam-in-time spectrophotometers. 

Figure 7.14. Schematic diagram of two types of double-beam spectrophotometers. A The double-beam-in-space configuration. B The double-beam-in-time configuration.

The spectrometer system for AAS can be configured as a single-beam system, as shown in Fig. 6.8, as a double-beam system, shown in Fig. 6.14, or as a pseudo-double-beam system, which will not be discussed. (See the reference by Beaty and Kerber for a description of this system.) Note that in AAS the sample cell is placed in front of the monochromator, unlike UV/VIS spectrometers for molecular absorption or spectrophotometry, where the sample is placed after the monochromator. 

Figure 6.14 Double-beam AAS configuration. [From Beaty and Kerber, used with permission of PerkinElmer, Inc. (www.perkinelmer.com).]...

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