Triangular mode

Mossbauer spectra are usually recorded in transmission geometry, whereby the sample, representing the absorber, contains the stable Mossbauer isotope, i.e., it is not radioactive. A scheme of a typical spectrometer setup is depicted in Fig. 3.1. The radioactive Mossbauer source is attached to the electro-mechanical velocity transducer, or Mossbauer drive, which is moved in a controlled manner for the modulation of the emitted y-radiation by the Doppler effect. The Mossbauer drive is powered by the electronic drive control unit according to a reference voltage (Fr), provided by the digital function generator. Most Mossbauer spectrometers are operated in constant-acceleration mode, in which the drive velocity is linearly swept up and down, either in a saw-tooth or in a triangular mode. In either case. 

Pulsed-force mode AFM (PFM-AFM) is a method introduced for fast mapping of local stiffness and adliesion with lower required data storage than recording force-distance curves at each point on the x-y plane [115]. A sinusoidal or triangular modulation is applied between the tip and sample (either via lever or sample piezo) at a lower frequency than that of either the piezo or cantilever resonance frequency. Tip and sample then come... 

Fig. 3.2 Triangular velocity reference signal top) and drive error signal bottom) of a Mossbauer drive operating in constant acceleration mode. The error signal is taken from the monitor output F of the drive control unit (see Fig. 3.1). Usually it is internally amplified by a factor of 100. Here, the deviations, including hum, are at the 2%o level of the reference. The peaks at the turning points of the triangle are due to ringing of the mechanical component, induced by the sudden change in acceleration (there should be no resonance line at the extremes of the velocity range)...

Fig. 3.3 Velocity control and synchronization of data recording by the multi-channel analyzer (MCA) operated in MCS mode with 512 channels. For the common triangular velocity profile shown here the spectrum is recorded twice, because each velocity increment is reached upon sweeping up and down. The sense of the velocity scales may also be opposite to that shown here, which means the MCA sweep may also start at...

Fig. 3.10 Variation of the spectrometer aperture as a function of the source motion for Mossbauer spectrometers operated in constant acceleration mode with triangular velocity profile, and the resulting nonlinear baseline distortion of the unfolded raw spectra. For simplicity a point-source is adopted, in contrast to most real cases (Rib mm active spot for Co in Rh)...

Trifluorophosphane can behave as a /x3 donor towards a triangular palladium core.559,360 The symmetrically bridging / -coordination mode has little precedent for tertiary ligands based on Group 15 atoms. The synthesis of a Pd1 dimer featuring a strongly bonded symmetrically bridging /i2-phosphole unit, which is the first example of this coordination mode for a tertiary phosphane, has been reported.561... 

Dy3+-Dy3+ ferromagnetic coupling has also been observed in a double chain based on the triangular motif (topologic mode (B) in Scheme 4.1) [74]. Slow relaxation is observed (A = 44.2K, r0 = 2.4 X 10-8 s) but its ID origin is not demonstrated, and the onset of 3D ordering is visible at low temperature. 

As a main point of this subsection,186 it is shown that due to sufficiently strong lateral interactions of adsorbed molecules on a two-dimensional triangular lattice, the spectral line for collective vibrations manifests some characteristic peculiar relationships between its dephasing-induced broadening and the resonance width 77 for the low-frequency mode The line width changes as Tj n(l/rf) for surface-normal and as rjm for surface-parallel molecular orientations, and takes nonzero values (independent of 77) for inclined molecules with the inclination angle ranging from 47° to 90°. 

Boriskina, S.V., Benson, T.M., Sewell, P., and Nosich, A.I., 2005, Optical modes in imperfect 2-D square and triangular microcavities, IEEE J. Quantum Electron., 41(6) 857-862. 

The simultaneous function of a transition metal atom as a lone-pair acceptor and as a cluster vertex atom is realized in [(77 -Ge9)Cu(ry -Geg)] (Fig. 5j), in which the two [Geg]" units are connected in an r/ - and an r/" -fashion to the same Cu ion. Transition metal bridges between Geg clusters are also found in various other coordination modes in [Ge9(/i -Au)3Geg] (Fig. 5k), three bridging Au atoms each are coordinated by two Ge atoms of two different Geg units in an almost linear way and entertain aurophUic interactions within the resulting triangle of Au" " ions two [GegR3] anions are coordinated via their triangular face to ( M = Zn, Cd,... 

Uwada T, Asahi T, Masuhara H, Ibano D, Fujishiro M, Tominaga T (2007) Multiple resonance modes in localized surface plasmon of single hexagonal/triangular gold nanoplates. Chem Lett 36(2) 318-319... 

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