“…We compare this theory with our results. Table lists the measured signs and values of compounds I , II , and other metal clusters that we studied before. ,,− It is evident that the measured signs of n 2 in all the clusters are consistent with the theory if the bandgap energy is replaced by the position of the lowest absorption peak (ℏω 0 ). Although compounds I and II have similar structures, replacing atom W for Mo results in a red-shift for the lowest absorption band, as shown in Figure , due to the heavy-atom effect.…”
Section: Resultssupporting
confidence: 64%
“…This performance is comparable to the limiting behavior observed in C 60 , which has been widely investigated as one of the best optical limiting materials. , The origin of the observed RSA in compound I or II can be attributed to excited-state absorption. We have performed time-resolved nonlinear transmission studies on ( n -Bu 4 N) 4 [Mo 8 Cu 12 O 8 S 24 ], a mixed metal cluster that has a similar nest-shaped structure, and the results revealed that the triplet−triplet transitions should be a responsible mechanism. , 4 …”
A new cluster compound [WOS 3 Cu 3 I(py) 5 ] (I) was synthesized by substitution reactions of (Et 4 N) 3 [WOS 3 -Cu 3 I 4 ] with pyridine and structurally determined by X-ray diffraction. It crystallizes in monoclinic, space group C2/c (No. 15), a ) 24.341(1), b ) 10.020(4), c ) 26.64(1) Å, V ) 6424(3) Å 3 , and Z ) 8. The cluster has a nest-shaped skeleton. The nonlinear optical properties of both I and [MoOS 3 Cu 3 I(py) 5 ] (II) in acetonitrile solutions were measured using a Z-scan technique with 7-ns and 532-nm laser pulses. Compound I possesses a self-focusing property (n 2 ) 1.6 × 10 -9 cm 2 W -1 M -1 ), while compound II exhibits a self-defocusing property (n 2 ) -1.3 × 10 -10 cm 2 W -1 M -1 ). Both compounds show reverse saturable absorption (R 2 ) 1.5 × 10 -4 and 2.5 × 10 -5 cm W -1 M -1 for compounds I and II, respectively). We demonstrate that the nonlinear refraction of a mixture containing the two compounds can be altered from self-focusing, through a state where self-lensing disappears, to self-defocusing by varying the ratio of the two compounds.
“…We compare this theory with our results. Table lists the measured signs and values of compounds I , II , and other metal clusters that we studied before. ,,− It is evident that the measured signs of n 2 in all the clusters are consistent with the theory if the bandgap energy is replaced by the position of the lowest absorption peak (ℏω 0 ). Although compounds I and II have similar structures, replacing atom W for Mo results in a red-shift for the lowest absorption band, as shown in Figure , due to the heavy-atom effect.…”
Section: Resultssupporting
confidence: 64%
“…This performance is comparable to the limiting behavior observed in C 60 , which has been widely investigated as one of the best optical limiting materials. , The origin of the observed RSA in compound I or II can be attributed to excited-state absorption. We have performed time-resolved nonlinear transmission studies on ( n -Bu 4 N) 4 [Mo 8 Cu 12 O 8 S 24 ], a mixed metal cluster that has a similar nest-shaped structure, and the results revealed that the triplet−triplet transitions should be a responsible mechanism. , 4 …”
A new cluster compound [WOS 3 Cu 3 I(py) 5 ] (I) was synthesized by substitution reactions of (Et 4 N) 3 [WOS 3 -Cu 3 I 4 ] with pyridine and structurally determined by X-ray diffraction. It crystallizes in monoclinic, space group C2/c (No. 15), a ) 24.341(1), b ) 10.020(4), c ) 26.64(1) Å, V ) 6424(3) Å 3 , and Z ) 8. The cluster has a nest-shaped skeleton. The nonlinear optical properties of both I and [MoOS 3 Cu 3 I(py) 5 ] (II) in acetonitrile solutions were measured using a Z-scan technique with 7-ns and 532-nm laser pulses. Compound I possesses a self-focusing property (n 2 ) 1.6 × 10 -9 cm 2 W -1 M -1 ), while compound II exhibits a self-defocusing property (n 2 ) -1.3 × 10 -10 cm 2 W -1 M -1 ). Both compounds show reverse saturable absorption (R 2 ) 1.5 × 10 -4 and 2.5 × 10 -5 cm W -1 M -1 for compounds I and II, respectively). We demonstrate that the nonlinear refraction of a mixture containing the two compounds can be altered from self-focusing, through a state where self-lensing disappears, to self-defocusing by varying the ratio of the two compounds.
“…On the other hand, the OL behavior of those clusters with cubane-like and pentanuclear planar “open” skeletons can be definitively attributed to the RSA mechanism under ns pulses irradiation ,,,,, where the absorption of clusters is weak at low incident light energy but becomes extremely strong under intense light radiation (RSA effect). Cubane-like clusters with trianionic and neutral skeletons comprise the largest group among various skeletons of clusters and have been extensively reported for NLO studies, which include anionic clusters of type [R 4 N] 3 [MO n S 4– n M′ 3 YL 3 ], ,,,− neutral clusters [MS 4 M′ 3 Y(PPh 3 ) 3 ], ,, or [MOS 3 Cu 3 Y(2-pic) 3 ] − type clusters with M = Mo, W; M′ = Cu, Ag; Y, L = Cl, Br, I; R = Et, Bu; n = 0, 1. It is also accepted that those clusters with a skeleton supported by S 2 P(OR) 2 ligands, for example, [MO n S 4– n M′ 3 (PPh 3 ) 3 {S 2 P(OR) 2 }] (M = Mo, W; M′ = Cu, Ag; R = Et, Pr i , Bu, Bu i , CH 2 Ph; n = 0, 1), − may also be ascribed as distorted cubane-like shape clusters (Table ).…”
The control of luminous radiation has extremely important implications for modern and future technologies as well as in medicine. In this Review, we detail chemical structures and their relevant photophysical features for various groups of materials, including organic dyes such as metalloporphyrins and metallophthalocyanines (and derivatives), other common organic materials, mixed metal complexes and clusters, fullerenes, dendrimeric nanocomposites, polymeric materials (organic and/or inorganic), inorganic semiconductors, and other nanoscopic materials, utilized or potentially useful for the realization of devices able to filter in a smart way an external radiation. The concept of smart is referred to the characteristic of those materials that are capable to filter the radiation in a dynamic way without the need of an ancillary system for the activation of the required transmission change. In particular, this Review gives emphasis to the nonlinear optical properties of photoactive materials for the function of optical power limiting. All known mechanisms of optical limiting have been analyzed and discussed for the different types of materials.
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