A method to reconstruct full three-dimensional photofragment distributions from their two-dimensional (2D) projection onto a detection plane is presented, for processes in which the expanding Newton sphere has cylindrical symmetry around an axis parallel plane. The based on: (1) onion-peeling polar coordinates [Zhao et al., Rev. Sci. Instrum. 73, 3044 (2002)] contribution 2D events outside bisecting are subtracted at incrementally decreasing radii; and (2) ideas borrowed basis set expansion...

The H + H(2) exchange reaction constitutes an excellent benchmark with which to test dynamical theories against experiments. D(2) (vibrational quantum number v = 0, rotational j 0) has been studied in crossed molecular beams at a collision energy of 1.28 electron volts, the use technique Rydberg atom time-of-flight spectroscopy. experimental resolution achieved permits determination fully rovibrational state-resolved differential cross sections. high-resolution data allow detailed assessment...

We have carried out a systematic crossed molecular beam study of the hydrogen exchange reaction in H+D2→HD+D isotopic form at two collision energies: 0.53 and 1.28 eV. The Rydberg atom time-of-flight method was used to measure D-atom product angle-velocity distribution. For first time ro-vibrational quantum state resolved differential cross sections for title were measured, which can directly be compared theoretical predictions this detailed level. Experimental results are from both quasi...

The crossing of two electronic potential surfaces (a conical intersection) should result in geometric phase effects even for molecular processes confined to the lower surface. However, recent quantum simulations hydrogen exchange reaction (H + H2 --> H) have predicted a cancellation such when product distributions are integrated over all scattering angles. We used simple topological argument extract paths with different senses from nuclear wave function that encircles intersection. In...

The photodissociation of jet-cooled IBr molecules has been investigated at numerous excitation wavelengths in the range 440–685 nm using a state-of-art ion imaging spectrometer operating under optimal conditions for velocity mapping. Image analysis provides precise threshold energies ground, I(2P3/2)+Br(2P3/2), and first excited [I(2P3/2)+Br(2P1/2)] dissociation asymptotes, electronic branching into these two active product channels, recoil anisotropy each set products, as function...

The H+D2(v=0,j=0)→HD(v′,j′)+D isotopic variant of the hydrogen atom exchange reaction has been studied in a crossed molecular beam experiment at collision energy 2.20 eV. Kinetic spectra nascent D atoms were obtained by using Rydberg time-of-flight technique. extensive set collected permitted derivation rovibrationally state-resolved differential cross sections center-of-mass frame for most internal states HD product molecules, allowing direct comparison with theoretical predictions....

The torsional motions of jet-cooled 1,4-bis(phenylethynyl)benzene (BPEB), a prototype molecular wire, were studied using cavity ring-down spectroscopy in the first UV absorption band (316-321 nm). spectrum 1,4-bis(phenylethynyl)-2,3,5,6-tetradeuteriobenzene was also recorded gas phase. Both spectra successfully simulated simple cosine potentials to describe motions. ground-state barrier rotation estimated be 220-235 cm(-1), which is similar that diphenylacetylene (tolane). Complementary DFT...

The H++D2(v=0,j=0)→HD+D+ reaction has been theoretically investigated by means of a time independent exact quantum mechanical approach, wave packet calculation within an adiabatic centrifugal sudden approximation, statistical model, and quasiclassical trajectory calculation. Besides probabilities as function collision energy at different values the total angular momentum, J, special emphasis made two specific energies, 0.1 0.524eV. occurrence distinctive dynamical behavior these energies is...

The hydrogen exchange reaction H+D2(v=0,j=0)→HD(v′,j′)+D was investigated at collision energies between 1.27 and 1.30 eV in a high resolution crossed beam experiment. angle-velocity distribution of nascent D-atoms measured using the technique Rydberg atom time-of-flight spectroscopy. this allows identification individual ro-vibrational states associated HD product molecule. Calculations done on Liu–Siegbahn–Truhlar–Horowitz (LSTH) potential energy surface (PES) explicitly including Geometric...

A recent puzzle in nonadiabatic quantum dynamics is that geometric phase (GP) effects are present the state-to-state opacity functions of hydrogen-exchange reaction, but cancel out integral cross sections (ICSs). Here authors explain this result by using topology to separate scattering amplitudes into contributions from Feynman paths loop opposite senses around conical intersection. The clockwise-looping pass over one transition state (1-TS) and scatter positive deflection angles;...

The scattering of highly excited hydrogen Rydberg atoms, H*(n = 36), with deuterium molecules in their rovibrational ground state, D2(v 0, j 0), has been investigated at a relative collision energy 0.53 eV. Time-of-flight distributions elastically/inelastically scattered H* atoms and reactively D* have measured different laboratory angles. extracted rovibrationally resolved state the HD product from reactive collisions resemble closely those reported for corresponding ion–molecule reaction,...

The hydrogen exchange reaction in its H+D2(v=0,j=0)→HD(v′=0,j′)+D isotopic variant has been investigated theoretically and experimentally at the collision energies 0.52 eV, 0.531 eV 0.54 eV. A detailed comparison of converged quantum mechanical scattering calculations state-to-state molecular beam experiments allowed a direct assessment quality different ab initio potential energy surfaces used calculations, strongly favors newly refined version Boothroyd–Keogh–Martin–Peterson surface....

Scattering measurements performed at an energy slightly higher than that of the lowest crossing between ground and first electronically excited state H3 system are reported. The essentials reactive dynamics describable in terms a classical motion nuclei on adiabatic electronic potential.

The state selective photodissociation of acetylene, C2H2/C2D2, was studied in the wavelength range 121.2–132.2 nm by high resolution Rydberg atom time-of-flight measurements on atomic fragment, H/D. In region members all four series and highly excited Ẽ valence were selectively using tunable vacuum-ultraviolet laser radiation. lifetime states which varied from 58 fs to more than 2 ps. Formation ethynyl radical its X̃ electronic ground first electronically à is observed with practically no...

A quasiclassical trajectory study of the state specific H+D2(υ=0,j=0)→HD(υ′=0,j′=0)+D reaction at a collision energy 1.85eV (total 2.04eV) found that scattering is governed by two unexpected and dominant new mechanisms, not direct recoil as generally assumed. The mechanisms involve strong interaction with sloping potential around conical intersection, an area surface previously considered to have much effect upon reactive scattering. Initial investigations indicate more than 50% could be...

We have demonstrated a new, accessible and economical technique, dubbed photostop, for producing high densities of trappable molecules. Direct measurements are presented NO molecules produced with narrow velocity distribution centered at zero in the laboratory frame. NO2, initially cooled pulsed molecular beam, is photodissociated such that recoil photofragments cancels out beam. NO(X^2Pi_3/2, v=0, J=1.5) observed up to 10 mircoseconds after dissociation event probe volume an estimated...

The formation of bromine atoms in their ground 2P3/2o (Br) and spin–orbit excited 2P1/2o (Br*) states as a result photolysis Br2 has been investigated at 260 nm 22 different wavelengths the range 360–580 using technique photofragment ion imaging. Image analysis yields both angular distributions branching ratios photofragments various wavelengths, which serve to confirm extend previously reported measurements these quantities.

The photodissociations of jet-cooled IBr and Br2 molecules have been investigated using high resolution ion imaging methods, at excitation energies just above the thresholds for forming, respectively, I(2P3/2o)+Br(2P3/2o) Br(2P3/2o)+Br*(2P1/2o) products from parent in their v″=0 levels. For such molecules, we observe both cases, that fragments with larger recoil velocities markedly reduced angular anisotropy, whereas those photolysis v″=1 show an essentially constant, limiting anisotropy....

The time-delayed forward scattering mechanism recently identified by Althorpe et al. [Nature (London) 416, 67 (2002)] for the H+D2(v=0,j=0)→HD(v′=3,j′=0)+D reaction was analyzed using quasiclassical trajectory (QCT) methodology. QCT results were found to match quantum wavepacket snapshots of al., albeit without effects. Trajectories on fly investigate dynamics atoms during reaction. dominant progresses from hard collinear impacts, leading direct recoil, toward glancing impacts. increased...

Photoinduced Fe-to-bpy charge transfer in [{Cp(dppe)Fe}(mu-C[triple bond]CC[triple bond]N){Re(CO)(3)(bpy)}]PF(6) has been observed by ps-TRIR spectroscopy, supported UV-Vis/IR spectroelectrochemistry and DFT calculations.