Scan speed higher

Due to the limited dynamic range the QIT is not a particularly good analyzer for quantification. For pure samples the problem is less pronounced, but if a background is present the background ions will constitute a substantial portion of the total number of ions entering the QIT and, hence, affect the quality of the quantification. Typical scan speeds arc 5 kTh/s (several commercial systems offer the possibility of different scan speeds). Higher resolution is attained by reducing the scan speed. 

Non-Linear Ion Trap with Higher Scan Speed, Higher Mass Resolution, and Extended Charge Capacity... 

Different options are available for LC-MS instruments. The vacuum system of a mass spectrometer typically will accept liquid flows in the range of 10-20 p,L min-1. For higher flow-rates it is necessary to modify the vacuum system (TSP interface), to remove the solvent before entry into the ion source (MB interface) or to split the effluent of the column (DLI interface). In the latter case only a small fraction (10-20 iLrnin ) of the total effluent is introduced into the ion source, where the mobile phase provides for chemical ionisation of the sample. The currently available commercial LC-MS systems (Table 7.48) differ widely in characteristics mass spectrometer (QMS, QQQ, QITMS, ToF-MS, B, B-QITMS, QToF-MS), mass range m/z 25000), resolution (up to 5000), mass accuracy (at best <5ppm), scan speed (up to 13000Das-1), interface (usually ESP/ISP and APCI, nanospray, PB, CF-FAB). There is no single LC-MS interface and ionisation mode that is readily suitable for all compounds... 

PDA detectors can be operated at rapid data acquisition rates (up to 40 Hz) and are the most common used. Quadrupole MS systems are capable of supplying sufficient spectra for peak. For reliable component assignment, of course, TOF-MS systems possessing higher scan speed can be used. 

The greatly reduced double-layer capacitance of microelectrodes, associated with their small area, results in electrochemical cells with small RC time constants. For example, for a microdisk the RC time constant is proportional to the radius of the electrode. The small RC constants allow high-speed voltammetric experiments to be performed at the microsecond timescale (scan rates higher than 106V/s) and hence to probe the kinetics of very fast electron transfer and coupling chemical reactions (114) or the dynamic of processes such as exocytosis (e.g., Fig. 4.25). Such high-speed experiments are discussed further in Section 2.1. 

Fig. 2. SEM micrograph of a rapidly electron-beam-annealed amorphous Si film that was thermally evaporated on a silica substrate. The 20-keV, 1-//A electron beam was focused to 2 /im and raster scanned at a rate of 2.5 cm sec-1, (a) Shows a periodic crescent-shaped explosive crystallization pattern, (b) Two different types of explosive crystallization features appear at slightly higher scan speed.

Fig. 3. Explosive crystallization in a-Si by rapid argon-laser scanning, (a) At a scan speed of 85 cm sec-1 both explosive solid-phase crystallization and liquid-phase crystallization are exhibited, (b) Two different types of solid phase crystallization are Observed at a scan speed of 900 cm sec 1, (c) The situation is the same as that in (b) but an even higher scan speed of 1000 cm sec 1 is used. [From Bensahel and Auvert (1983b).]...

Furthermore, half-ellipsoid voxels and half-cylindrical rod shapes were fabricated by TP polymerization where a single voxel was obtained by a laser power of 50 pW and an exposure time of 0.5 s [135]. The half-cylindrical rod shapes based on poly(methylmethacrylate) possess a higher reflective index compared to air of about 0.5. Hence, this material can be used as waveguide material. The channel waveguide fabricated using a scanning speed of 40 pm/s and an input laser power of 500 pW of a femtosecond laser beam with a 0.65 NA microscope objective exhibits a width of 2 pm. In a similar way, a grating was made with 10 lines per 50 pm [135]. 

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