Bunched mode,

Fig. 9.13 Time evolution of the NFS intensity for various temperatures around the HS-LS transition of [Fe(tpa)(NCS)2]. The measurements were performed at 1D18, ESRF in hybrid-bunch mode. The left-hand side shows measurements in the transition region performed with decreasing temperature and the right-hand side with increasing temperature. (The spectral patterns at comparable temperatures do not match due to hysteresis in the spin-transition behavior). The points give the measured data and the curves are results from calculations performed with CONUSS [9, 10]. The dashed line drawn in the 133 K spectmm represents dynamical beating. (Taken from [41])...

The prerequisite for such a measurement is information about the starting time. This can be provided by the pulsed time structure of the primary photon beam (single-bunch mode for operating the electron storage ring), or by a reaction product of the photoprocess which is in coincidence with the emitted electron and can be another electron or a photon. More details on time-of-flight electron spectrometry are given in Section 10.1. 

Figure 4.10 The time structure of the X-ray beam derives from that of the electrons (or positrons) in the storage ring. The electrons travel in the ring in bunches and thus the radiation is emitted in pulses. The values shown are for the Daresbury SRS in multibunch mode. In single bunch mode the light pulse occurs each orbital period of 0.321 jus.

This uses a multipole wiggler and will have operational modes for focussed Laue diffraction work and monochromatic experiments. The small source sizes should allow an equivalently small focal spot from a grazing incidence mirror system. Exposure times in the microsecond range for a macromolecular crystal should be feasible. Depending on the current achieved in single bunch mode it may be possible, at least for smaller unit cell sizes, to record a Laue pattern from one of the single bunches with an intrinsic time resolution therefore of the bunch width. (Feasibility experiments of this kind have been conducted at CHESS but on an undulator (Szebenyi et al 1989).)... 

One major advantage of linacs that operate in a single-bunch mode is the short pulse width, typically 30 ps FWHM, which enables the investigation of very fast reactions. A magnetic pulse compression system installed on the 20-MeV electron linac beamline at Argonne National Laboratory generates 5-ps pulses (7). 

Record spectra using a pulse (1 ns, 12 kHz) liquid metal source ( Ga, 15 keV) operating in the bunched mode to provide good mass resolution (m/Am = 2000 measured at m/z 43). 

Spectroscopic mode also referred to as Bunched mode. This is used when optimal secondary ion mass resolution is needed. Note This comes at the cost of image spatial resolution. 

Spectroscopic mode, also referred to as Bunched mode, brings together the ions within a particular primary ion pulse such that they arrive at the sample s surface... 

As indicated earlier, Physical Electronics introduced the HR mode , to provide improved high mass and high spatial resolution at the same time. This is implemented while in the Spectroscopic or Bunched mode through re-design of the LMIG region so as to minimize the energy spread of the primary ion beam pulses. It is quoted that 500 nm spatial resolution at moderate beam currents with sub nanosecond pulse widths is attainable. 

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