FLASH PHOTOLYSIS OF N-ACETYL-L-TRYPTOPHANAMIDE: ANALYSIS OF TRANSIENTS EMPLOYING VIDICON TUBE DETECTION*

Abstract— An improved method for recording transient absorption spectra obtained by flash photolysis is described. The detection system, comprising a vidicon tube coupled to a multichannel analyzer, is shown to permit the rapid acquisition of accurate and precise spectra spanning any 360 nm interval within the 200 to 1100 nm wavelength range. The successful dissection of the complex spectrum obtained when N-acetyl-L-tryptophanamide is flashed under nitrogen-saturated conditions is utilized to highlight the capabilities of the detection system. This analysis suggests that the observed radicals must originate, in part, from an oxygen sensitive long-lived precursor which is not the triplet state.     

Regge phenomenology

A review is presented of Regge phenomenology in high energy two-body and quasi-two-body scattering.     

Axial vector meson production

Recently available differential cross section and density matrix information on π^?p → B^?p at 4 GeV/c are successfully described in terms of t channel exchanges and s channel absorptive effects. The s channel helicity amplitude which is dominant at small |t| (zero net helicity flip ω exchange) is found to have a zero at ?t = 0.2 GeV². SU(3) and higher symmetries are used to predict cross sections for further axial vector meson production processes, in particular non-diffractive A₁ production. The importance of these processes with regard to Regge phenomenology and meson spectroscopy is emphasized.     

Regge pole and cut behaviour at Fermilab energies

Prompted by some unusual features of the np charge-exchange cross sections recently measured at Fermilab, we study this process over the entire energy range in an attempt to clarify its exchange amplitude structure. Comparison with all the other two-body processes so far measured at Fermilab (π^?p → π⁰n, νn, ω⁰n and elastic scattering) allows one to draw useful conclusions concerning the required J-plane structure of Regge cut models. We show that the shrinkage properties and helicity dependence of Regge cuts must be more complicated than current models suggest. We also present evidence that the Williams (or “poor man's absorption”) model for π exchange is incorrect at high energies.