We report fluorescence imaging of single dye molecules on a glass substrate by two-photon excitation with femtosecond pulses from a mode-locked Ti:sapphire laser. The single-molecule images exhibit a high signal to background ratio (>30:1) and a high spatial resolution (fwhm < /3). A quadratic intensity dependence of single-molecule emission rate is experimentally verified, and single-molecule ...

In accurate radiotherapy, energy spectra of high energy x-ray greatly affect the accuracy of dose calculation. Conventional discrete method failed to realize the stable solution, and the Schiff formula could not reflect the practical geometric shape of different linac system that showed the limitation to apply to other linacs. To obtain the photon energy spectra of linac in radiotherapy effecti...

Having accurate and comprehensive photon diagnostics for the X-ray pulses delivered by free-electron laser (FEL) facilities is of utmost importance. Along with various parameters of the photon beam (such as photon energy, beam intensity, etc.), the pulse length measurements are particularly useful both for the machine operators to measure the beam parameters and monitor the stability of the mac...

Inclusive transverse momentum spectra of photons and π 0 s about mid–rapidity are presented for 197 Au+ 197 Au collisions at √ s NN = 130 GeV. Photon pair conversions have been reconstructed from charged tracks measured with the central Time Projection Chamber (TPC) of STAR. Contributions of the π 0 → γγ decay in the inclusive photon spectra have been studied. It was found that this contributio...

Pulsed-field-ionization zero-kinetic-energy photoelectron spectra of jet-cooled allyl radical (C(3)H(5)) have been recorded following single-photon and resonant multiphoton excitation. Simulations based on an orbital ionization model and rovibronic photoionization selection rules reliably describe the observed intensity distributions in the photoelectron spectra obtained from single-photon exci...

Photoelectron spectra of Au, with n = 2-4 are reported. Due to the relatively high photon energy used in our experiment (hv=6.424 eV) and the energy resolution of about 50 meV, various transitions into excited states of the neutral clusters are resolved. It is demonstrated that photoelectron spectra can serve as a map of the electronic states of a cluster, while the high resolution of the reson...

Two-photon absorption spectra in absolute cross-section values are presented for a number of octaethyl-, tetraphenyl-, and tetrabenzo-substituted porphyrins. In excitation spectral region of 710–810 nm, the two-photon absorption efficiency is resonantly enhanced due to nearby Q(0–0) one-photon transition. The cross-section value calculated directly from the groundand excited-state absorption pa...

We explore excitation and ionization by neutron impact as a novel tool for the investigation of electron-electron correlations in helium. We present single- and double-ionization spectra calculated in accurate numerical ab initio simulations for incoming neutrons with kinetic energies of up to 150 keV. The resulting electron spectra are found to be fundamentally different from photoionization o...

Ž . We have observed laser-jitter-enhanced high-resolution spectra of three hyperfine states in the ground level H of 4 Pr :Y SiO using coherent population trapping and phase-correlated four-wave mixing. We have also observed optical 2 5 Raman pulse excited two-photon spectral hole-burning. The observed high-resolution spectra are due to a laser-jitter-suppressed Raman coherence window in an in...

We investigate coherent single-photon transport in a waveguide-QED structure containing two giant atoms. The unified analytical expressions of the scattering amplitudes applicable for different topological configurations are derived. spectroscopic characteristics parameter regimes, especially asymmetric Fano line shapes and electromagnetically induced transparency (EIT)-like spectra, analyzed d...