A5034497047- Nonlinear Optical Materials Studies
- Porphyrin and Phthalocyanine Chemistry
- Laser-Matter Interactions and Applications
- Advanced Fluorescence Microscopy Techniques
- Photochemistry and Electron Transfer Studies
- Photochromic and Fluorescence Chemistry
- Photorefractive and Nonlinear Optics
- Luminescence and Fluorescent Materials
- Photodynamic Therapy Research Studies
- Spectroscopy and Quantum Chemical Studies
- Photoreceptor and optogenetics research
- Advanced Fiber Laser Technologies
- Nanoplatforms for cancer theranostics
- Quantum optics and atomic interactions
- Nonlinear Optical Materials Research
- Photonic and Optical Devices
- Analytical Chemistry and Sensors
- Spectroscopy Techniques in Biomedical and Chemical Research
- Photoacoustic and Ultrasonic Imaging
- Laser Design and Applications
- Spectroscopy and Laser Applications
- Advanced Optical Imaging Technologies
- X-ray Diffraction in Crystallography
- Cell Image Analysis Techniques
- Crystallization and Solubility Studies
Montana State University
2015-2024
National Institute of Chemical Physics and Biophysics
2015-2024
Polish Academy of Sciences
2004-2015
Institute of Organic Chemistry
2012-2015
Museum of the Rockies
2015
UiT The Arctic University of Norway
2015
Arlington Free Clinic
2014
University of Oxford
2004-2012
University of Florida
2010
Sensopath Technologies (United States)
2008
We present absolute two-photon absorption (2PA) spectra of 15 commercial organic dyes covering an extended range excitation wavelengths, 550-1600 nm. The 2PA is measured with estimated accuracy +/-10% using a femtosecond fluorescence method. data are corrected for the variations pulse duration and beam profile wavelength, applicable as reference standards measurements.
We have used protein engineering to expand the palette of genetically encoded calcium ion (Ca(2+)) indicators include orange and improved red fluorescent variants, validated latter for combined use with optogenetic activation by channelrhodopsin-2 (ChR2). These feature intensiometric signal changes that are 1.7- 9.7-fold relatively progenitor Ca(2+) indicator, R-GECO1. In course this work, we discovered a photoactivation phenomenon in that, if not appreciated accounted for, can cause...
We present the two-photon absorption (2PA) spectra of a series conjugated porphyrin dimers and show that they possess extremely large intrinsic (femtosecond) peak 2PA cross sections, up to sigma2 = 1 x 104 GM in near-IR region; these are among highest values measured for any organic molecule. Moreover, we demonstrate second-order perturbation theory applied simple three-level model gives perfect quantitative description observed section. By comparing all factors with those corresponding...
Two-photon absorption spectra (2PA) of a series conjugated dimers and the corresponding monomer were studied in near-IR region. All show very large peak cross section values, σ2 = (3−10) × 103 GM (1 1 10-50 cm4 s photon-1), which is several hundred times larger than that obtained for same We explain such dramatic cooperative enhancement by combination factors, as strong lowest one-photon Q-transition, better resonance conditions three-level system, excited-state singlet−singlet transition,...
We present, for the first time, unambiguous spectroscopic evidence of strong cooperative enhancement two-photon absorption (TPA) in a series dendritic macromolecules. The maximum TPA cross section increases proportion to N2, where N = 2, 4, 6 is number constituent identical chromophore units. show that facilitated by quasi-planar structure, which allows direct interbranch conjugation throughout molecule.
Abstract Purpose: The aim of this study was to show that novel photodynamic therapy (PDT) sensitizers can be activated by two-photon absorption in the near-IR region spectrum and show, for first time, such activation lead tumor regressions at significant tissue depth. These experiments also evaluated effects high-energy femtosecond pulsed laser irradiation on normal tissues characterized response xenograft tumors our PDT protocols. Experimental Design: Human small cell lung cancer (NCI-H69),...
We report what is to our knowledge a record high value for an intrinsic two-photon absorption (TPA) cross section, sigma(2) = 11 x 10(-47)> cm>(4)> s photon(-1) molecule(-1), measured with femtosecond pulses in new dendrimer molecule comprising 29 repeat units of 4, 4(?)-bis(diphenylamino)stilbene chromophore. measure the dependence TPA on excitation wavelength three consecutive generations and show that maximum increases faster than total number stilbene chromophores. This result indicates...
Airborne contaminants, e.g., bacterial spores, are usually analyzed by time-consuming microscopic, chemical, and biological assays. Current research into real-time laser spectroscopic detectors of such contaminants is based on resonance fluorescence. The present approach derives from recent experiments in which atoms molecules prepared one (or more) coherent laser(s) probed another set lasers. However, generating using maximally oscillation macromolecules having an enormous number degrees...
We present the two-photon absorption (2PA) spectra of a series conjugated porphyrin oligomers containing N = 2, 4, 8, and ca. 13 monomer units, meso-meso connected with butadiyne linkers. demonstrate that, in coplanar double-strand arrays, self-assembled upon addition 4,4'-bipyridyl, conjugation length increases dramatically, leading to very strong cooperative enhancement 2PA. analyze scaling 2PA both rotationally free single-strand arrays show how effective cases is linked observed...
We study two-photon absorption (2PA) in two series of new free-base porphyrins with 4-(diphenylamino)stilbene or 4,4'-bis-(diphenylamino)stilbene (BDPAS) attached via π-conjugating linkers at the porphyrin meso-position. show that this substitution modality increases 2PA cross section Soret band region (excitation wavelength 750−900 nm) core by nearly 2 orders magnitude, from σ2 ≈ 10 GM for meso-phenyl-substituted analogue to 103 ethynyl-linked BDPAS−porphyrin dyad. The properties are...
To explore the photophysics of platinum acetylide chromophores with strong two-photon absorption cross-sections, we have investigated synthesis and spectroscopic characterization a series complexes that feature highly π-conjugated ligands substituted π-donor or -acceptor moieties. The molecules (numbered 1−4) considered in present work are analogs bis(phenylethynyl)bis(tributylphosphine)platinum(II) complexes. Molecule 1 carries two alkynyl-benzothiazolylfluorene ligands, molecule 2 has...
Degenerate two-photon absorption (2PA) of a series organic fluorophores is measured using femtosecond fluorescence excitation method in the wavelength range, λ2PA = 680-1050 nm, and ~100 MHz pulse repetition rate. The function relative 2PA spectral shape obtained with estimated accuracy 5%, absolute cross section at selected wavelengths 8%. Significant improvement achieved by means rigorous evaluation quadratic dependence signal on incident photon flux whole comparing results from two...
A combined experimental and theoretical study of the two-photon absorption (2PA) properties a series quadrupolar molecules possessing highly electron-rich heterocyclic core, pyrrolo[3,2-b]pyrrole, is presented. In agreement with quantum-chemical calculations, large 2PA cross-section values, σ2PA ≈10(2) -10(3) GM (1 GM=10(50) cm(4) s photon(-1) ), are observed at wavelengths 650-700 nm, which correspond to allowed but one-photon forbidden transitions. The calculations also predict that...
Summary form only given. The goal of this paper is, first, to present the two-photon absorption (TPA) spectra in absolute cross section values (/spl sigma//sub 2/) for a number porphyrins with gradually varying optical properties, and, second, show that TPA efficiency these molecules can be resonantly enhanced near-IR region. were obtained by tuning an parametric amplifier.
We study the enhancement of two-photon absorption (TPA) in a series porphyrins and tetraazaporphyrins by measuring absolute TPA cross sections with 100-fs-duration pulses two ranges laser wavelengths, from 1100 to 1500 700 800 nm. The section Q transition region is σ2∼1–10 GM (where 1 GM=10-50 cm4 s-1 photons-1), value that explained partial lifting prohibition due parity selection rule. In Soret we find σ2 ∼1 order magnitude owing transition, which acts as near-resonance intermediate state,...
We demonstrate persistent storage, recall, and conjugation of picosecond light signals from various model objects, including a coin, by making use coherent optical responses in photochemically active media. A simple linear theory holographic storage playback both the spatial temporal behavior signal field is shown to describe well experimental results obtained utilizing octaethylporphin-doped polystyrene at 1.8 K as spectrally selective recording material.
We have investigated the photophysical properties and intracellular behaviour of a series hydrophilic conjugated porphyrin dimers. All dimers exhibit intense linear absorption at 650–800 nm high singlet oxygen quantum yields (0.5–0.9 in methanol), as required for an efficient sensitiser photodynamic therapy (PDT). They also fluorescence 700–800 nm, with up to 0.13 methanol, show extremely large two-photon maxima 8,000–17,000 GM near-IR. The aggregate aqueous solution, but aggregation is...
The linear and nonlinear optical properties of a series cross-conjugated platinum(II) acetylide complexes that contain extended p-(phenylene vinylene) chromophores are reported. exhibit very high femtosecond two-photon absorption (2PA) cross section values (σ(2) up to 10,000 GM), as measured by transmission (NLT) excited fluorescence (2PEF) methods. large 2PA sections span broad range wavelengths, 570-810 nm, they overlap with the triplet state absorption. Spectral coincidence is key feature...
We study instantaneous two-photon absorption (2PA) in a series of nominally quasi-centrosymmetric trans-bis(tributylphosphine)-bis-(4-((9,9-diethyl-7-ethynyl-9H-fluoren-2-yl) ethynyl)-R)-platinum complexes, where 11 different substituents, R = N(phenyl)2(NPh2), NH2, OCH3, t-butyl, CH3, H, F, CF3, CN, benzothiazole, and NO2, represent range electron-donating (ED) electron-withdrawing (EW) strengths, while the Pt core acts as weak ED group. measure 2PA cross section 540-810 nm excitation...