Ireneling Li

Controlling the alignment of neutral iodine molecules in the elliptical channels of AlPO4-11 crystals

AlPO4-11 (AEL) single crystal provides well-aligned one-dimensional elliptical nanochannels, wherein neutral iodine molecules can be trapped and aligned. Since the iodine molecules are well accommodated in the matrix of the AEL single crystal, it offers us a good example for studying polarized Raman spectra in a controllable way. Polarization dependence of Raman intensity of the iodine molecular vibration modes indicates that the iodine molecules are strictly oriented in two directions, either along the long axis of the elliptical channel or along the AEL channel direction.

Synthesis and characterization of iodine molecular wires in channels of zeolite AEL single crystals

Well-aligned iodine molecular wires were synthesized by means of loading iodine molecules in the elliptical nanometer-scale channels of AlPO(4)-11 (AEL) single crystals. Polarized Raman spectra reveal that the iodine molecular wires are oriented along the crystal channel direction by lining iodine molecules on the yz plane, where y and z represent the channel direction and the major-axial direction of the elliptical rings, respectively. Natural iodine wires are unstable, but they are very stable in the AEL channels. The template technique offers us an ideal platform to study the novel properties of these molecular wires.

Resonant Raman study of confined Se single helix and Se8 rings

Electron-phonon coupling in Se species confined in the nanoporous matrix has been investigated by using resonant Raman spectra performed with several different laser lines from deep blue to near infrared. The spectra strongly depend on the energies of the excitation laser lines. The one-phonon symmetric A1 modes for Se single helix and Se8 rings are enhanced in the vicinity of their absorption bands. Detailed analysis shows that the Raman band in the high-frequency range of 450–550cm−1 is composed of three individual second-order Raman bands for the confined Se species. These two-phonon Raman shifts occur at twice the frequency shift of the first-order Raman lines, and their intensities are also enhanced when the excitation laser energy matches an electronic transition in Se nanospecies.

Passively Q-switching induced by the smallest single-walled carbon nanotubes

We report a passively Q-switched erbium-doped fiber laser (EDFL) by using the smallest single-walled carbon nanotubes (SWNTs) with a diameter of 0.3u2009nm as the saturable absorber. These small SWNTs are fabricated in the nanochannels of a ZnAPO-11 (AEL) single crystal. By inserting one of the AEL crystal into an EDFL cavity pumped by a 980u2009nm laser diode, stable passive Q-switching is achieved for a threshold pump power of 206.2 mW, and 4.73u2009μs pulses with a repetition rate of 41.78u2009kHz and an average output power of 3.75 mW are obtained for a pump power of 406 mW.

Synthesis of large MgAPO-11 single crystals in a F− free system

The synthesis process of large magnesium substituted AlPO4-11 single crystals (MgAPO-11) under hydrothermal conditions has been reported. The crystal size and morphology sensitively depend on crystallization conditions and gel compositions. The addition of HF acid in the gel undermines rather than favours the growth of MgAPO-11 single crystals. Using the optimal gel composition with magnesium oxide as the magnesium source, large MgAPO-11 single crystals with good quality have been synthesized in a F− free system. The typical crystal dimensions are 25 × 157 ×254 μm3, the synthesis temperature is 180 °C, and the crystallization period is 60 hours.