Wavelength dependent studies of nonlinear absorption in zinc meso-tetra(p-methoxyphenyl)tetrabenzoporphyrin (Znmp TBP) using Z-scan technique

2001 ◽  
Vol 05 (07) ◽  
pp. 549-554 ◽  
Author(s):  
N. K. M. NAGA SRINIVAS ◽  
S. VENUGOPAL RAO ◽  
D. V. G. L. N. RAO ◽  
B. K. KIMBALL ◽  
M. NAKASHIMA ◽  
...  
Keyword(s):  
Excited State ◽  
Cross Sections ◽  
Nonlinear Absorption ◽  
Visible Region ◽  
Excited State Absorption ◽  
Photon Absorption ◽  
Dispersion Data ◽  
Level Model ◽  
Scan Data ◽  
Two Photon Absorption Coefficient

We report here, our experimental results and theoretical analysis of the dispersion data of nonlinear absorption in zinc meso-tetra-(p-methoxyphenyl)tetrabenzoporphyrin (ZnmpTBP). Using a ns optical parametric oscillator (OPO) we obtain the open aperture Z-scan data over the visible region starting from 480 nm to 600 nm. We use a more general five-level model for evaluating the excited state parameters like excited state absorption coefficients, two-photon absorption coefficient, etc. Due to its large excited state absorption cross-sections this material acts as a very good candidate for a broadband optical limiter in the visible region.

New experimental method for determining the S1 → Sn absorption spectrum of highly fluorescent dyes

1993 ◽  
Vol 71 (1-2) ◽  
pp. 59-65 ◽  
Author(s):  
Marie-Claire Gazeau ◽  
Véronique Wintgens ◽  
Pierre Valat ◽  
Jean Kossanyi ◽  
Denis Doizi ◽  
...  
Keyword(s):  
Excited State ◽  
Cross Sections ◽  
Fluorescent Dyes ◽  
Visible Region ◽  
Excited State Absorption ◽  
Absorption Cross ◽  
Excited Singlet ◽  
Uv Visible ◽  
The One ◽  
State Concentration

A new method has been developed to measure the excited-state absorption cross sections σ1n, of highly fluorescent dyes. which gives excited singlet-state absorption (ESSA) spectra over most of the UV–visible region, including the one where the fluorescence occurs. The error in the σ1n values depends on that for the singlet excited-state concentration. Our method used benzophenone as an actinometer to determine the excited-state concentration. Rhodamine 6G was used to test the method; the ESSA spectrum obtained shows a maximum around 530 nm with an excited-state absorption cross section σ1n value of 2.08 × 10−16 cm2. Our results are discussed and compared with those reported in the literature.

PICOSECOND-INDUCED NONLINEAR ABSORPTION IN LIQUID CRYSTAL MEDIA

1995 ◽  
Vol 04 (01) ◽  
pp. 245-260 ◽  
Author(s):  
K. J. McEWAN ◽  
R. C. HOLLINS
Keyword(s):  
Experimental Data ◽  
Liquid Crystal ◽  
Excited State ◽  
Nonlinear Absorption ◽  
Excited State Absorption ◽  
Photon Absorption ◽  
Isotropic Phase ◽  
Pump Probe ◽  
Two Photon Absorption ◽  
Two Photon

The contributions to the nonlinear absorption of liquid crystal media in their isotropic phase are measured using a picosecond pump/probe technique at 587 nm. Good agreement between the experimental data and theory is obtained by assuming that two-photon absorption and excited state absorption dominate the nonlinear optical response. The important parameters are extracted from the experimental data and it is shown that the nonlinear absorption depends strongly on the molecular structure. The lifetime of the excited state is measured and found to compare well with the fluorescence lifetime.

OPTICAL LIMITING STUDIES IN PHOTOREFRACTIVE PURE AND IRON-DOPED Bi12SiO20 CRYSTALS

2000 ◽  
Vol 09 (02) ◽  
pp. 217-225 ◽  
Author(s):  
P. SREERAMANA AITHAL ◽  
P. PREM KIRAN ◽  
D. NARAYANA RAO
Keyword(s):  
Excited State Absorption ◽  
Optical Limiting ◽  
Photon Absorption ◽  
Limiting Behavior ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Iron Incorporation ◽  
Optical Limiter ◽  
Level Model

Optical limiting characteristics of pure and 150 ppm Fe-doped Bi 12 SiO 20 (BSO:Fe) crystals are studied at high intensity nanosecond pulse regime. When the input light is at 532 nm and at 595 nm with 6 ns pulse duration, a good optical limiting behavior is observed due to simultaneous effect of trap assisted excited state absorption and two photon absorption. The precise role of the internal defects due to impurity centers present in the crystal lattice is explained on the basis of a four level model. This study reveal that the increased nonlinear absorption due to iron incorporation in BSO makes it an excellent passive optical limiter.

scholarly journals Impact of the Subunit Arrangement on the Nonlinear Absorption Properties of Organometallic Complexes with Ruthenium(II) σ-Acetylide and Benzothiadiazole as Building Units §

Inorganics ◽  
2019 ◽  
Vol 7 (5) ◽  
pp. 67
Author(s):  
Eleonora Garoni ◽  
Alessia Colombo ◽  
Kenji Kamada ◽  
Claudia Dragonetti ◽  
Dominique Roberto
Keyword(s):  
Electron Acceptor ◽  
Cross Sections ◽  
Nonlinear Absorption ◽  
Organometallic Complexes ◽  
Photon Absorption ◽  
Absorption Cross ◽  
Absorption Properties ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Resonance Enhancement

In this paper, the nonlinear absorption properties of two complexes consisting of Ru(C≡CPh)(C≡C)(dppe)2 (dppe = Ph2PCH2CH2PPh2) as electron donor (D) and 4,7-di(2-thienyl)benzo[c][1,2,5]thiadiazole as electron acceptor (A) units in two different arrangement, i.e., A–D–A and D–A–D, are presented. They were measured in solution by the femtosecond open-aperture Z-scan method. The complexes show moderate two-photon absorption cross-sections σ(2) of several hundred to one thousand GM (here 1 GM = 10−50 cm4 s molecule−1 photon−1). Although they are formed by the same building units, it was found that the two-photon absorption values of the D–A–D arrangement are six times higher than that of the A–D–A one. This difference can be explained by the number of metal cores (one or two ruthenium centers), the geometrical configurations of the complexes (more or less planar), and the resonance enhancement by lowering the intermediate state.

Cross sections for excited-state absorption in a Pt:ethynyl complex

2001 ◽  
Vol 18 (3) ◽  
pp. 358 ◽  
Author(s):  
T. J. McKay ◽  
J. Staromlynska ◽  
J. R. Davy ◽  
J. A. Bolger
Keyword(s):  
Excited State ◽  
Cross Sections ◽  
Excited State Absorption

Infrared saturable absorbers. Part II: Intensity dependent transmission of SF6 at 936.8 wave numbers

1977 ◽  
Vol 55 (18) ◽  
pp. 1569-1579
Author(s):  
George F. Caudle ◽  
Jerald R. Izatt ◽  
Tuan-Kay Lim
Keyword(s):  
Cross Sections ◽  
Average Power ◽  
Excited State Absorption ◽  
Laser Pulses ◽  
Beam Power ◽  
Hole Burning ◽  
Saturable Absorbers ◽  
Pulse Transmission ◽  
Band Absorption ◽  
Level Model

Due to rotational hole burning Q-switched laser pulses sometimes saturate a molecular absorber more effectively than CW laser radiation. The absorption by SF6 of frequencies near the P(28) line in the 10.6 μm CO2 laser band provides an interesting example. In this case it has been reported elsewhere that for peak intensities [Formula: see text] an increase in pulse intensity produces a monotonic increase in transmission whereas the CW transmission decreases monotonically with intensity. We report new measurements made over a wider range of laser power levels and at several SF6 pressures, which show that the global behavior of the transmission as a function of average beam power is quite similar for both CW and pulsed radiation. The pulse transmission is somewhat greater at all power levels, but when the average power is sufficiently high the growth of hot-band absorption and possibly other intensity dependent changes in the ground and excited-state absorption cross sections cause the transmission to fall well below its low-intensity value for CW radiation and pulses alike. The experimental transmission curves for both cases display as many as three extrema and cannot be explained, even qualitatively, by the five-level model used in the earlier work. The extended results are consistent with the modified five-level model presented in Part I of this pair of papers.

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