Kinetics of Thermal Dissociation–Restoration Processes of J-Aggregate

Abstract

GaN etching damage characteristics by capacitively coupled radio frequency Kr and Ar plasmas have been found to differ significantly, on the basis of experimental and simulation results. The morphology of a GaN surface etched by Kr plasma is as smooth as that of the asgrown surface, and is independent of gas pressure and etching time. The agreement between the experimental and simulated etching depths for the Kr plasma, which are lower than those for the Ar plasma, indicates a significant contribution to the GaN damage of the physical etching effect. In contrast, Ar plasma etching produces a rough surface, which is dependent on gas pressure and etching time, and appears to be due to a chemical effect. The difference in the GaN surface morphologies etched by the Kr and Ar plasmas may be attributed to the different depths etched for these two plasmas. Moreover, the simulation shows that, for the Kr plasma, Ga is preferentially etched from GaN, whereas the preferential etching of N occurs for the Ar plasma. The difference in preferential etching between the Kr and Ar plasmas may be related to the difference between the GaN surface morphologies etched by these two plasmas.

Generation of disk-like domains with nanometer scale thickness in merocyanine dye LB film induced by hydrothermal treatment

“…In our previous papers, we pointed out that the growth of the new phase of the J-band is well described by a first-order reaction between Band I (blue-shift-dimer band located at 500 to 515 nm) and Band III (J-band located in the range of 590 to 598 nm which includes both of the original band at 590 to 594 nm and the reorganized one at 597 to 599 nm), while the Band II component (monomer band located at 545 to 555) remains almost unchanged [17,19,22,26]. The reason of the optical isotropy of the reorganized J-band (at 597 to 599 nm) is considered to be due to that crystallites of the J-aggregate grow randomly in the film plane starting from the blue-shift dimers.…”

“…The as-deposited J-band originally located around 590 nm is reorganized by HTT to form a new phase associated with a further narrowing and a red shift of the peak [16-26]. …”

“…Recently, we have found that the hydrothermal treatment (HTT), which is a heat treatment under relative humidity of 100%, is effective for controlling the dye aggregation states when it is applied to the well-known MS-C 20 binary LB film [ 16 - 26 ]. The as-deposited J-band originally located around 590 nm is reorganized by HTT to form a new phase associated with a further narrowing and a red shift of the peak [ 16 - 26 ].…”

“…We have already investigated kinetics of hydrothermally induced reorganization of J-aggregate in the mixed MS-C 20 LB system and have pointed out that the UV-visible absorption spectra can be deconvoluted to three components: Band I (centered at 500 to 515 nm), Band II (centered at 545 to 555 nm), and Band III (centered at 590 to 598 nm) [ 17 , 19 , 22 , 26 ]. Band I, Band II, and Band III are assigned as the blue-shifted dimer, monomer, and red-shifted J-aggregate, respectively.…”

“…The second stage is characterized as the reorganization of Band III (centered at 597 to 599 nm) from Band I (500 to 515 nm). Since the component of Band II (centered at 545 to 555 nm) is almost unchanged throughout the whole HTT process, we have described that the growth and decay processes in the second stage are assumed to be a first-order reaction between Band I and Band III components [ 22 , 26 ].…”