HRTOF Technique

The time-of-flight spectrum of the H-atom product from the H20 photodissociation at 157 nm was measured using the HRTOF technique described above. The experimental TOF spectrum is then converted into the total product translational distribution of the photodissociation products. Figure 5 shows the total product translational energy spectrum of H20 photodissociation at 157.6 nm in the molecular beam condition (with rotational temperature 10 K or less). Five vibrational features have been observed in each of this spectrum, which can be easily assigned to the vibrationally excited OH (v = 0 to 4) products from the photodissociation of H20 at 157.6 nm. In the experiment under the molecular beam condition, rotational structures with larger N quantum numbers are partially resolved. By integrating the whole area of each vibrational manifold, the OH vibrational state distribution from the H2O sample at 10 K can be obtained. In... 

In these experiments, there was no double-resonance tagging, so all of the HI moieties were available for photodissociation. What is observed experimentally is the resulting atomic hydrogen time-of-flight distribution which is obtained by using the HRTOF technique (Ashfold et al. 1992 Schneider et al. 1990 Wen et al. 1994). This method provides excellent resolution and S/N compared to other TOF methods. The dominant features (solid curves) are due to HI monomer. However, upon magnification, features are seen that are due to... 

In early days, HRTOF technique was used to study gas-phase photodissociation whose products contain hydrogen atoms (or deuterium atoms), for example, a variety of hydrogen halides, HCN, H2O, H2S, NHj, PHj, C2H2, CH3SH, CH3NH2, HCOOH, HFCO, HN3 [8, 10, 37]. These processes constitute a major chemical... 

The key technique of HRTOF is to produce a laser at 121.6 nm and overlap this laser with another laser beam at 365 nm exactly both in space and in time. The laser system of the experiment is introduced here, as shown in Fig. 2.5. 

Using HRTOF crossed molecular beam technique, we studied the F( P) + D2 DF + D reaction systematically. The differential cross sections and the relative integral cross sections in this reaction were provided. We measured the F( P3/2)/ F ( Pi/2) r tio in the F atom beam and thus got the F( P3/2)/F ( Pi/2) reactivity ratio, which is in perfect agreement with the theoretical results. In Sect. 4.1 of this chapter, we review non-adiabatic efifects in the F -b H2 system the measurement of the F( P3/2)/F ( Pi/2) ratio in the F atom beam is described in Sects. 4.2, 4.3 presents the crossed molecular beam experimental results and discussion summary is given in the last section. 

---