Time-of-flight spectrum

Figure A3.9.3. Time-of-flight spectra for Ar scattered from Pt(l 11) at a surface temperature of 100 K [10], Points in the upper plot are actual experimental data. Curve tinough points is a fit to a model in which the bimodal distribution is composed of a sharp, fast moving (lienee short flight time), direct-inelastic (DI) component and a broad, slower moving, trapping-desorption (TD) component. These components are shown...

Figure B2.3.5. Typical time-of-flight spectra of DF products from the F + D2 reaction [28]- The collision energies and in-plane and out-of-plane laboratory scattered angles are given in each panel. The DF product vibrational quantum number associated with each peak is indicated. Reprinted with pennission from Faiibel etal [28]. Copyright 1997 American Chemical Society.

Fig. 19. Time of flight spectra of the H atom product from the ()(1 I)) + H2 —> OH + H reaction at -50° laboratory scattering angle at the collision energy of 1.3kcal/mol.

Fig. 7. Time-of-flight spectra for Zr and Nb+C2H4 at con = 14, 9, and 6 kcal/mol from top to bottom, respectively. Note that at con = 6 kcal/mol, the slower peak disappears in the Zr system. Reprinted with permission from Ref. 121.

Fig. 9. Time-of-flight spectra for non-reactively scattered yttrium atoms at indicated lab angles for the Y + CH3OH reaction at Eco = 28.1 kcal/mol. Fits data generated using the CM distributions shown in Fig. 10.

A second feature of the Y + CH3OH reaction that is common to many metal reactions is the presence of competing reaction channels, in this case YH2+H2CO and YOCH3+H. Time-of-flight spectra for both these products are shown in Fig. 11. The corresponding lab angular distributions and CM distributions used to fit the TOF spectra are shown in Fig. 12. 

Data were also recorded for the reaction of Y with all four butene isomers at a lower collision energy of 11.0 kcal/mol. Time-of-flight spectra were taken at the CM angle for each isomer. As shown in Fig. 39 for Y + cis-2-butene, only YC4H6 products were observed. This collision energy corresponded to the thermodynamic threshold for YCH2 formation, and was only slightly above threshold for the YH2 channel (Fig. 32). 

Fig. 39. Time-of-flight spectra for rn/e values corresponding to (a) YC4H6, (b) YH2, and (c) YCH2 products from the Y + cis-2-butene reaction at the CM angle for, n = 11.0 kcal/mol.

Fig. 42. Co(CbHb)CO time-of-flight spectra at indicated laborarory angles from photodissociation of Co(CbHb)(CO)2 at 355nm.

Fig. 19.11 (a) Time of flight spectra of Ba 6p3/2 s 7=1 autoionization electrons. Peak 1, decay into the Ba+ 6s continuum peak 2, into the Ba+ 5d3/215/2 continua peak 3, into the Ba+ 6p1/2 continuum. The drift length was approximately 10 cm. The spectra were recorded with a gate width of 14 ns. (b) The same as (a) but with a drift length of approximately 45 cm and a gate width of 6 ns (from ref. 25). 

In Fig. 19.11 we show the time of flight spectra, obtained with 0 = 0, for electrons from a 6p3/2 ns1/2 state lying above the 6p1/2 ionization limit.25 With a 10 cm flight path for the electrons, the electrons ejected in autoionization to the Ba+ 6s 1/2 and 5dj states are barely resolved, while with the higher resolution afforded by a 45 cm flight path the electrons from autoionization to the 6s1/2 and 5dj states are well resolved, showing little autoionization to the Ba+ 5d5/2 state. To... 

Safford and Naumann (128) have shown that the time-of-flight spectra for 4.6M solutions of KF, KC1, CsCl, NaCl, and LiCl show peaks in the inelastic scattering region which coincide both in frequency and shape with the ice-like (structured) frequencies of pure water. Also, solutions of KSCN, KI, KBr, and NaC104 have lattice frequencies where they are found for water although in these cases apparently with less resolution and less intensity. Even an 18.5-M solution of KSCN showed a similar behavior. We take this to suggest that elements of water structure remain in these solutions (as discussed elsewhere in this paper, where we noted that the thermal anomalies occur at approximately the same temperatures, even for relatively concentrated solutions, as where they occur in pure water see also Ref. 103). 

For example, [94] reports a direct process for investigating ZnO polarity based on the analysis of time-of-flight spectra in ion-scattering experiments low-energy ion beams are scattered over the surface of the layer, causing it to be sputtered by the ion bombardment. The detector allows the time-resolved detection of the Zn-particle stream and of the scattered primary ions. The extent of O termination and Zn termination for the layer can be calculated from the difference between these signals. 

Fig. 19 The time-of-flight spectra obtained following irradiation of Fe(CO)5 with (a) ns and (b, c) fs laser pulses at 400 nm spectra were obtained using a linear (a, b) and high-resolution reflectron (c) mass detectors. Adapted from [48]...

Neutron time-of-flight spectra for molded polyetrafluoroethylene at six temperatures between 10° C and 100 C are reproduced in Fig. 9 (27). Unlike polyethylene and polypropylene, neutron scattering from poly-tetrafluoroethylene is expected to be mainly coherent. Thus, peaks may occur in the inelastic spectrum due to coherent scattering from individual lattice planes. However, measurements as a function of scattering angle... 

Neutron time-of-flight spectra (2<5) for Nylon-6 are given in Fig. 10. A comparison of NIS and infrared data for Nylon-6 (5, 16, 18, 37), and NIS and infrared spectra 30) for n-heptane is given in Table 3. The vibrations of the -( 112)5- segments in Nylon-6 are expected to occur below 600 cm-, where the intramolecular C-C-C deformation and C-C torsional modes in n-paraffins have been shown to occur (7). In view of the transferability established for the intramolecular force constants among the n-paraffins 33), it was of interest to test the degree to which they could be transferred to the —( 112)5 groups of Nylon-6. 

Figure 5 Values of cth/vd obtained from fitting individual time of flight spectra for the H20 / D20 data published in Ref. [Chatzidimi-triou-Dreismann 1997 (a)] as a function of scattering angle. Circles are for xd = 0.9, crosses for xd = 0.5 and squares for xd = 0.3. Within error at a given x d, there is no angular dependence...

Figure 2. Examples of time-of flight spectra for mixed H- and /9-hydratcd niobium [Karlsson 1999 Karlsson 2003 (b)].

Figure 4. Time-of-flight spectra at LAB angles 18, 30, and 8 with vibrational state assignments (data A, total calculated...

Clearly, the scattering intensities should be helped by carrying out the experiment at low surface temperatures and with relatively small wavevectors. In practice, however, one finds that the Weare criterion is overly severe and one is often able to discern distinct peaks in time-of-flight spectra due to single-phonon scattering events on top of a broad multiphonon background even for Debye-Waller exponents 2W 1. 

Figure 28. Time-of-flight spectra for KMnFs transformed to energy transfer distributions for several temperatures at incident angles 35° and 36°. The low-energy mode (arrows) seen on the creation side (negative energy transfer) at 36° is very close to the zone boundary and appears to be associated with the surface phase transition that occurs at 191 K. At 35° the low-energy peak corresponds to a mode further removed fiom the zone boundary, which persists up to high temperatures. (Reproduced from Fig. 18 of Ref. 92, with permission.)...

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