Photoelectron imaging and time of flight mass spectrometry are used to study the multiphoton ionization and dissociation of pyrrole and its cation following excitation at 243 nm and at 364.7 nm. Our results confirm the 8.2 eV ionization potential of pyrrole and the 9.2 eV ionization threshold for forming the 2B1 first excited state of the cation. Prompt photolysis of the N-H bond in neutral pyr...

Stochastic reconstruction techniques are developed for mapping the interior optical properties of tissues from exterior frequency-domain photon migration measurements at the air-tissue interface. Parameter fields of absorption cross section, fluorescence lifetime, and quantum efficiency are accurately reconstructed from simulated noisy measurements of phase shift and amplitude modulation by use...

IMAGING an object located in a highly scattering medium is a challenging problem with a wide range of applications in different fields: medicine, industry, defence and space. A better understanding of photon migration in turbid media has resulted in a surge of research interest in optical biomedical imaging. Limitations of X-ray imaging in detecting small lesions in tissues, in distinguishing m...

We describe an approach that combines clinical ultrasound and photon migration techniques to enhance the sensitivity and information content of diffuse optical tomography. Measurements were performed on a postmenopausal woman with a single 1.8 x 0.9 cm malignant ductal carcinoma in situ approximately 7.4 mm beneath the skin surface (UCI IRB protocol 95-563). The ultrasound-derived information a...

Nature Materials 14, 924–930 (2015); published online 3 August 2015; retracted after print 24 November 2016. We wish to retract this Article due to concerns with some data related to upconversion in the solid-state samples presented in Fig. 4d,e, and to the reproducibility check of the triplet diffusion constant provided in the Supplementary Information. In this Article, we reported fast triple...

The use of perturbation and differential Monte Carlo (pMC/dMC) methods in conjunction with nonlinear optimization algorithms were proposed recently as a means to solve inverse photon migration problems in regionwise heterogeneous turbid media. We demonstrate the application of pMC/dMC methods for the recovery of optical properties in a two-layer extended epithelial tissue model from experimenta...

Mesenchymal stem cells (MSCs) participate in regeneration of tissues damaged by ionizing radiation. However, radiation can damage MSCs themselves. Here we show that cellular morphology, adhesion and migration abilities were not measurably altered by photon or carbon ion irradiation. The potential for differentiation was unaffected by either form of radiation, and established MSC surface markers...

A simplified approach is proposed to simulate the fluorescence signal from a fluorophore submerged inside a turbid medium using the Monte Carlo method. Based on the reversibility of photon propagation, the fluorescence signal can be obtained from a single Monte Carlo simulation of the excitation light. This is computationally less expensive and also allows for the direct use of well-validated n...

in this work we investigate the thermal entanglement between two-level atoms and photons in a nonlinear cavity. we consider intensity-dependent couplings and calculate the negativity, as a measure of atom-photonentanglement. the cavity is assumed to be at a temperature t, so that all number of photons, and at the same time, both atomic states, with definite probabilities, are present. we then d...

Nature Materials 14, 924–930 (2015); published online 3 August 2015; retracted after print 24 November 2016. We wish to retract this Article due to concerns with some data related to upconversion in the solid-state samples presented in Fig. 4d,e, and to the reproducibility check of the triplet diffusion constant provided in the Supplementary Information. In this Article, we reported fast triple...