Dynamic saturable optical nonlinearities in free base tetrapyridylporphyrin

2003 ◽  
Vol 07 (06) ◽  
pp. 452-456 ◽  
Author(s):  
Newton M. Barbosa Neto ◽  
Leonardo De Boni ◽  
José J. Rodrigues ◽  
Lino Misoguti ◽  
Cléber R. Mendonça ◽  
...  
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Optical Nonlinearities ◽  
Free Base ◽  
Photophysical Parameters ◽  
Crossing Time ◽  
532 Nm

Dynamic optical nonlinearities in free base tetrapyridylporphyrin ( H 2 TPyP ) solutions were investigated at 532 nm with the Z-scan technique. We observed a reverse saturable absorption process that was found to have a fast contribution related to the singlet population and a slow accumulative contribution arising from the triplet population. The optical excitations and subsequent relaxations can be interpreted with a five-energy-level diagram that allows determination of the excited states photophysical parameters such as triplet and singlet absorption cross-sections and the intersystem crossing time.

Nonlinear Optical Properties of Modified Carbocyanines

1997 ◽  
Vol 479 ◽  
Author(s):  
Nansheng Tang ◽  
Weijie Su ◽  
Thomas M. Cooper ◽  
Daniel G. McLean ◽  
Donna M. Brandelik ◽  
...  
Keyword(s):  
Cross Sections ◽  
Excited State Absorption ◽  
Laser Pulses ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Pump Probe ◽  
Chirped Pulses ◽  
Molecular Hyperpolarizability ◽  
Meso Position ◽  
532 Nm

AbstractWe studied the optical nonlinearities of modified 3,3′-diethylthiadicarbocyanine iodides (X-DTDCI) in dimethyl sulfoxide (DMSO) solutions (X = H, Cl, Br at meso position) by a pump-probe technique with crossed polarized chirped laser pulses at room temperature. Reverse-saturable-absorption (RSA) with monoexponential lifetimes is observed at 532 nm in all the samples studied. We determined the effective excited-state absorption cross-sections and their lifetimes for all the samples investigated and found that they clearly correlate to the substituent X at the meso position. Empowered by the chirped pulses, a much faster nonlinearity with a decay time of ˜3.1 ps that is much shorter than the laser pulses used, is unveiled in Cl-DTDCI. We expressed both the absorptive and the refractive part of this fast nonlinearity as the equivalent molecular hyperpolarizability γ1212 and found γ1212 = (8.1 + i9.8) × 10−32erg−1.

PICOSECOND REVERSE SATURABLE ABSORPTION AND OPTICAL LIMITING IN FULLERENES AND THEIR METAL DERIVATIVES

2000 ◽  
Vol 09 (04) ◽  
pp. 505-521 ◽  
Author(s):  
J. CALLAGHAN ◽  
W. J. BLAU ◽  
F. Z. HENARI
Keyword(s):  
Excited State ◽  
Cross Sections ◽  
Ground State ◽  
Population Level ◽  
Optical Limiting ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Picosecond Pulses ◽  
Metal Derivatives ◽  
532 Nm

Investigations of the reverse saturable absorption behaviour of Fullerenes C 60 and C 70 and some of their Pt and Pd metal derivatives have been carried out with picosecond pulses at 532 nm. From intensity dependent transmission measurements, coupled with a population level kinetic analysis, excited state cross sections were determined for the materials. These show that C 60 possesses the largest excited state to ground state cross-section ratio and that, of the materials studied, it offers the best optical limiting ability around 532 nm. C 70, due to its large ground state absorption, has been shown not to be an efficient limiter. The metal derivatives perform better than C 70 but less efficiently than C 60.

Effects of extending the π-conjugation of the acetylide ligand on the photophysics and reverse saturable absorption of Pt(ii) bipyridine bisacetylide complexes

2016 ◽  
Vol 18 (41) ◽  
pp. 28674-28687 ◽  
Author(s):  
Taotao Lu ◽  
Chengzhe Wang ◽  
Levi Lystrom ◽  
Chengkui Pei ◽  
Svetlana Kilina ◽  
...  
Keyword(s):  
Excited State ◽  
Excited States ◽  
Substituent Effect ◽  
Excited State Absorption ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Triplet Excited State ◽  
Near Ir ◽  
Terminal Substituent ◽  
Acetylide Ligand

Extending the acetylide ligand π-conjugation diminishes the terminal substituent effect on the lowest excited states, but expands the triplet excited-state absorption to the near-IR region.

scholarly journals Aspect-ratio Dependence of Optical Nonlinearities on Resonance with Longitudinal Surface Plasmon in Au Nanorods: Unique Character versus Common Behavior

2018 ◽  
Vol 1 (1) ◽  
pp. 001-007
Author(s):  
Science Nature
Keyword(s):  
Aspect Ratio ◽  
Surface Plasmon ◽  
Nonlinear Behavior ◽  
Dipole Approximation ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Optical Nonlinearities ◽  
Ratio Dependence ◽  
Unique Character ◽  
Metal Metal

Unique character and common behavior are two distinguished things. In frontier nanoscience and nanotechnology, unique characters were normally obtained in some novel exotics materials such as metal-metal core-shell materials, metallic-semiconducting hybrid nanomaterials, and  organic-inorganics complex nano-compounds. On the other hand, normal behavior of natural phenomena including in nano-size objects were obviously predicted based on their exact size related to confinement effect, and capability to interact with another physical system  in nature.  Here, we report an example of unique character due to evolution nonlinear behavior observed in gold nanorod with their aspect-ratio dependence of optical nonlinearities investigated by femtosecond Z-scan measurements closed to resonance longitudinal surface plasmon peak in gold nanorods (Au NRs). Saturable absorption manifests itself at low excitation (laser irradiances < ~7.0 GW/cm2), while reverse saturable absorption dominates at higher excitation. Both the nonlinear processes are found to increase with the aspect ratio of Au NRs.  Based on the discrete dipole approximation, qualitative explanations are presented for the observed nonlinear behavior. While common behavior in metallic quantum dots or other shapes of metallic nanomaterials was not the significant in our observation.  

Photophysics and reverse saturable absorption of cationic dinuclear iridium(iii) complexes bearing fluorenyl-tethered 2-(quinolin-2-yl)quinoxaline ligands

2021 ◽  
Author(s):  
Cuifen Lu ◽  
Taotao Lu ◽  
Peng Cui ◽  
Svetlana Kilina ◽  
Wenfang Sun
Keyword(s):  
Excited State ◽  
Excited State Absorption ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Triplet Excited State ◽  
532 Nm

Dinuclear Ir(iii) complexes tethered by fluorenyl motif exhibited weak 1,3MLCT/1,3LLCT absorption at >500 nm, dual phosphorescence, broad triplet excited-state absorption, and reverse saturable absorption at 532 nm.

Anionic Surfactant Sensing by Optical Properties of Erythrosin B

2020 ◽  
Vol 18 (1) ◽  
pp. 43-46
Author(s):  
Zainab Saberi
Keyword(s):  
Optical Properties ◽  
Nonlinear Optical ◽  
Nonlinear Optical Properties ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Erythrosin B ◽  
Ctab Concentration ◽  
Dye Aggregation ◽  
Light Excitation ◽  
532 Nm

The nonlinear optical properties, absorbance and fluorescence spectra of Erythrosin B (ErB) aqueous solution in different CTAB concentration was studied. Z-scan technique under laser light excitation at 532 nm, was used for study reverse saturable absorption (RSA) of ErB. it was observed that the RSA of solution depend on CTAB concentration. A enhancing of absorbance and quenching of fluorescence is observed with increase of CTAB concentration in solution and the RSA can reduce the fluorescence intensity. It was proposed that the micelle can reduce the dye aggregation is solutions and it can affect on linear and nonlinear optical properties of ErB.

Reverse saturable absorption and anti-Stokes fluorescence in mesoionic compounds pumped at 532 nm

2001 ◽  
Vol 40 (9) ◽  
pp. 1389 ◽  
Author(s):  
Nikifor Rakov ◽  
Cid B. de Araújo ◽  
Gerd B. Rocha ◽  
Alfredo M. Simas ◽  
Petrônio A. F. Athayde-Filho ◽  
...  
Keyword(s):  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Anti Stokes ◽  
532 Nm

scholarly journals Determination of the absorption cross sections of higher-order iodine oxides at 355 and 532 nm

2020 ◽  
Vol 20 (18) ◽  
pp. 10865-10887
Author(s):  
Thomas R. Lewis ◽  
Juan Carlos Gómez Martín ◽  
Mark A. Blitz ◽  
Carlos A. Cuevas ◽  
John M. C. Plane ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Atmospheric Chemistry ◽  
Absorption Cross Section ◽  
Particle Formation ◽  
Absorption Cross ◽  
Iodic Acid ◽  
Iodine Oxides ◽  
532 Nm

Abstract. Iodine oxides (IxOy) play an important role in the atmospheric chemistry of iodine. They are initiators of new particle formation events in the coastal and polar boundary layers and act as iodine reservoirs in tropospheric ozone-depleting chemical cycles. Despite the importance of the aforementioned processes, the photochemistry of these molecules has not been studied in detail previously. Here, we report the first determination of the absorption cross sections of IxOy, x=2, 3, 5, y=1–12 at λ=355 nm by combining pulsed laser photolysis of I2∕O3 gas mixtures in air with time-resolved photo-ionization time-of-flight mass spectrometry, using NO2 actinometry for signal calibration. The oxides selected for absorption cross-section determinations are those presenting the strongest signals in the mass spectra, where signals containing four iodine atoms are absent. The method is validated by measuring the absorption cross section of IO at 355 nm, σ355nm,IO= (1.2±0.1) ×10-18 cm2, which is found to be in good agreement with the most recent literature. The results obtained are σ355nm,I2O3<5×10-19 cm2 molec.−1, σ355nm,I2O4= (3.9±1.2)×10-18 cm2 molec.−1, σ355nm,I3O6= (6.1±1.6)×10-18 cm2 molec.−1, σ355nm,I3O7= (5.3±1.4)×10-18 cm2 molec.−1, and σ355nm,I5O12= (9.8±1.0)×10-18 cm2 molec.−1. Photodepletion at λ=532 nm was only observed for OIO, which enabled determination of upper limits for the absorption cross sections of IxOy at 532 nm using OIO as an actinometer. These measurements are supplemented with ab initio calculations of electronic spectra in order to estimate atmospheric photolysis rates J(IxOy). Our results confirm a high J(IxOy) scenario where IxOy is efficiently removed during daytime, implying enhanced iodine-driven ozone depletion and hindering iodine particle formation. Possible I2O3 and I2O4 photolysis products are discussed, including IO3, which may be a precursor to iodic acid (HIO3) in the presence of HO2.

scholarly journals Partial Photoionization Cross Sections of Chromium from the Ground and Excited States

Atoms ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 51
Author(s):  
Oleg Zatsarinny ◽  
Swaraj Tayal
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Bound States ◽  
Close Coupling ◽  
R Matrix ◽  
Hartree Fock ◽  
Nonresonant Background ◽  
Ionic States ◽  
Matrix Calculation

Partial and total photoionization cross sections of iron-peak elements are important for the determination of abundances in late-type stars and nebular objects. We have investigated photoionization of neutral chromium from the ground and excited states in the low energy region from the first ionization threshold at 6.77 eV to 30 eV. Accurate descriptions of the initial bound states of Cr I and the final residual Cr II ionic states have been obtained in the multiconfiguration Hartree-Fock method together with adjustable configuration expansions and term-dependent non-orthogonal orbitals. The B-spline R-matrix method has been used for the calculation of photoionization cross sections. The 194 LS final ionic states of Cr II 3d44s, 3d34s2, 3d5, 3d44p, and 3d34s4p principal configurations have been included in the close-coupling expansion. The inclusion of all terms of these configurations has significant impact on the near-threshold resonance structures as well as on the nonresonant background cross sections. Total photoionization cross sections from the ground 3d54sa7S and excited 3d54sa5S, 3d44s2a5D, 3d54pz5P, and 3d44s4py5P states of Cr I have been compared with other available R-matrix calculation to estimate the likely uncertainties in photoionization cross sections. We analyzed the partial photoionization cross sections for leaving the residual ion in various states to identify the important scattering channels, and noted that 3d electron ionization channel becomes dominant at higher energies.

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