A high pressure Raman study on confined individual iodine molecules as molecular probes of structural collapse in the AlPO₄-5 framework

Abstract

The individual iodine molecules in the channels of AlPO4-5 can be regarded as molecular probes to detect its structural collapse.

Intrinsic and Extrinsic Responses of ZIF-8 under High Pressure: A Combined Raman and X-ray Diffraction Investigation

“…However, challenges still remain for current force fields to perfectly describe the continuous structural evolution of ZIF-8 owing to the complexity of the system. ,, Among all the experimental techniques, the widely used Raman spectroscopy has advantages in studying ZIF-8 since it is convenient in probing microscopic vibrations and is complementary to the X-ray results. Any subtle changes associated with the molecules or porous materials can be reflected in the vibrational spectra, and these can provide adequate information for probing into the host–guest interaction and framework modifications. − Recently, the adsorption behaviors and structural transformations of several porous MOFs upon gas adsorption have been investigated successfully at a microscopic level by Raman spectroscopy. − …”

Crystal Growth by Unidirectional Method ‐ A Generalized View on the Crystalline Perfection of the Uni‐Indexed, Bi‐Indexed, and Tri‐Indexed Plane Single Crystals

“…[44] In the case of the (1010) plane, the dominant Raman mode is shifted toward the lower wavenumber while one lattice Raman mode has disappeared and this can be convincing evidence for the increase of local lattice disorder in the grown crystal. [48][49][50][51][52][53][54][55] More interestingly, in the case of the (4211) plane, the lattice Raman mode is shifted from 201 to 192 cm −1 while here also one higher wavenumber lattice Raman mode has disappeared and such kind of significant changes in the Raman lattice modes clearly show the formation of local lattice disorder in the case of the (4211) plane. [48][49][50][51][52][53][54][55] The Differential Scanning Calorimetric (DSC) technique is well established to be one of the powerful tools to distinguish the crystalline and the amorphous states of the solid-state samples [56,57] such that the required DSC study is performed to reaffirm the degree of crystalline nature of the NSH sample with respect to their planes.…”

“…[ 48 ‐ 55 ] More interestingly, in the case of the (4211) plane, the lattice Raman mode is shifted from 201 to 192 cm −1 while here also one higher wavenumber lattice Raman mode has disappeared and such kind of significant changes in the Raman lattice modes clearly show the formation of local lattice disorder in the case of the (4211) plane. [ 48–55 ]…”

“…Furthermore, in justifying the outcomes of the indented research, Raman spectroscopic results can provide more inroads into the local disorder of the crystal structure. [43][44][45][46][47][48][49][50][51][52][53][54] The recorded lattice modes Raman spectra of the grown crystals and the observed lattice Raman modes are presented in Figure 3. Note that, in the case of NiSO 4 .6H 2 O for the (004) plane, the lattice Raman mode positions are observed at 210, 236, and 269 cm −1 such that the observed Raman band positions are well-matched with the previous reports.…”

Pressure‐induced insertion and transformation of N2 in the cavities of zeolitic imidazolate framework‐8: A Raman study

“…Here, the Raman characteristics of the confined nitrogen exhibit an ability to act as molecular probe to detect ZIF‐8 framework transformation, which is similar with the behavior of the iodine molecules in AFI channels. [ 48 ] When comparing the pressure coefficients in N 2 ‐ZIF‐8 system with those in N 2 ‐AFI system, [ 27 ] the coefficient (0.95 cm −1 /GPa) of the band ν′ in the 11.6 Å cavities of the flexible ZIF‐8 in the low‐pressure range below 5 GPa is about three times smaller than those of 3.3 and 2.9 cm −1 /GPa in AFI. A plausible interpretation is that the rigid one‐dimensional channels with a smaller size of 7.3 Å in AFI provide a more restrictive environment and probably exert a stronger compression on the confined nitrogen molecules.…”