One- and Two-Photon Absorption in CdS Nanodots and Wires: The Role of Dimensionality in the One- and Two-Photon Luminescence Excitation Spectrum

2014 ◽  
Vol 119 (2) ◽  
pp. 1260-1267 ◽  
Author(s):  
Alexander W. Achtstein ◽  
Ana Ballester ◽  
Jose L. Movilla ◽  
Jonas Hennig ◽  
Juan I. Climente ◽  
...  
2009 ◽  
Vol 27 (7) ◽  
pp. 1269-1279 ◽  
Author(s):  
Wenchao LI ◽  
Jikang FENG ◽  
Aimin REN ◽  
Xiangbiao ZHANG ◽  
Chiachung SUN

2004 ◽  
Vol 82 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Xin Zhou ◽  
Ai-Min Ren ◽  
Ji-Kang Feng ◽  
Xiao-Juan Liu

The one-photon absorption (OPA) properties of tetrabenzoporphyrins (TBPs) and phthalocyanines (Pcs) were studied using the semiempirical ZINDO method and time-dependent density functional theory (TDDFT), respectively. The compared results confirmed that the semiempirical ZINDO method was reasonably reliable when calculating the OPA of tetrabenzoporphyrins and phthalocyanines. On the basis of the OPA properties obtained from the ZINDO method, two-photon absorption (TPA) properties of two series of molecules were investigated, using ZINDO and sum-over-states (SOS) methods. The results showed that the TPA cross-sections of all molecules were in the range of 220.6 × 10–50 – 345.9 × 10–50 cm4·s·photon–1, which were in the same order of magnitude as the values reported in the literature. The relatively larger δ(ω) value for Pcs with respect to that for corresponding TBPs originates from larger intramolecular charge transfer, which can be characterized by the difference of dipole moment between S0 and S1 and the transition dipole moment between S1 and S5.Key words: two-photon absorption, ZINDO, sum-over-states, tetrabenzoporphyrin, phthalocyanines.


2000 ◽  
Vol 09 (02) ◽  
pp. 217-225 ◽  
Author(s):  
P. SREERAMANA AITHAL ◽  
P. PREM KIRAN ◽  
D. NARAYANA RAO

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.


2011 ◽  
Vol 91 (2) ◽  
pp. 248-257 ◽  
Author(s):  
Shuang Huang ◽  
Ai-Min Ren ◽  
Lu-Yi Zou ◽  
Yang Zhao ◽  
Jing-Fu Guo ◽  
...  

2004 ◽  
Vol 846 ◽  
Author(s):  
S. Polyutov ◽  
I. Minkov ◽  
F. Gel'mukhanov ◽  
K. Kamada ◽  
A. Baev ◽  
...  

ABSTRACTWe present a theory of two-photon absorption in solutions which addresses the formation of spectral shapes taking account of the vibrational degrees of freedom. The theory is used to rationalize observed differences between spectral shapes of one- and two-photon absorption. We elaborate on two underlying causes, one trivial and one non-trivial, behind these differences. The first refers simply to the fact that the set of excited electronic states constituting the spectra will have different relative cross sections for one-and two- photon absorption. The second reason is that the two-step and coherent two-photon absorption processes are competing, making the one-and two-photon spectral bands different even considering a single final state. The theory is applied to the N-101 molecule [di-phenyl-amino-nitro-stilbene] which was recently studied experimentally in the paper [ T.-C. Lin, G.S. He, P.N. Prasad, and L.-S. Tan, J. Mater. Chem., 14, 982, 2004.]


1996 ◽  
Vol 449 ◽  
Author(s):  
I. H. Libon ◽  
C. Voelkmann ◽  
D. Kim ◽  
V. Petrova-Koch ◽  
Y. R. Shen

ABSTRACTWe report the observation of UV photoluminescence (PL) from wurtzite GaN by multiphoton excitation. The dependence of the PL intensity on excitation intensity as well as PL excitation measurements with sub-bandgap photon energies indicate the existence of deep defect states centered at about 1.0 eV above the top of the valence band. This result was confirmed by a sum-frequency excitation spectrum. We correlate these measurements with the omnipresent yellow luminescence in GaN. Our two-photon PL excitation spectrum yields a two-photon absorption coefficient that agrees very well with theoretical predictions.


2014 ◽  
Vol 92 (4) ◽  
pp. 284-288
Author(s):  
Seyyed Hossein Asadpour ◽  
H. Rahimpour Soleimani

In this paper, the effect of microwave field on the transient and steady state response of the four-level inverted Y-type atomic system is investigated. It is found that the properties of transient and steady processes can be affected by microwave field. It is found that the absorption spectrum behaves differentially for single-photon absorption and two-photon absorption. Also it is observed that in the one-photon absorption, the microwave field can lead to the probe gain and for two-photon absorption case, the strong microwave can enhance the absorption.


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