Exciton energy transfer between the inner and outer tubes in double-walled carbon nanotubes

We have studied photoluminescence (PL) spectrum and dynamics of the inner nanotubes in double-walled carbon nanotubes (DWNTs) and compared PL properties between DWNTs and single-walled carbon nanotubes (SWNTs). The PL peak energies of the inner tubes are redshifted from those of SWNTs with the same chiral indices. This PL redshift is enhanced with an increase in the inner tube diameter. The PL lifetime of DWNTs increases with a decrease in the inner tube diameter. The diameter dependence of PL dynamics is explained by exciton energy transfer between the inner and outer tubes through Förster-type dipole-dipole interaction

Observation of charged excitons in hole-doped carbon nanotubes using photoluminescence and absorption spectroscopy

We report the first observation of trions (charged excitons), three-particle bound states consisting of one electron and two holes, in hole-doped carbon nanotubes at room temperature. When p-type dopants are added to carbon nanotube solutions, the photoluminescence and absorption peaks of the trions appear far below the E11 bright exciton peak, regardless of the dopant species. The unexpectedly large energy separation between the bright excitons and the trions is attributed to the strong electron-hole exchange interaction in carbon nanotubes

Femtosecond Excitation Correlation Spectroscopy of Single-Walled Carbon Nanotubes : Analysis Based on Nonradiative Multiexciton Recombination Processes

We studied the nonlinear time-resolved luminescence signals due to multiexciton recombination processes in single-walled carbon nanotubes (SWNTs) using femtosecond excitation correlation (FEC) spectroscopy. From theoretical analysis of the FEC signals, we found that the FEC signals in the long time range are dominated by the single exciton decay in SWNTs, where the exciton-exciton annihilation process is efficient. Our results provide a simple method to clarify the single exciton decay dynamics in low-dimensional materials.Comment: 21 pages, 5 figures; typos adde

Exciton localization of single-walled carbon nanotubes revealed by femtosecond excitation correlation spectroscopy

Photoluminescence (PL) dynamics in single-walled carbon nanotubes (SWNTs) has been studied by the femtosecond excitation correlation method with a 150 fs time resolution. The SWNT samples were synthesized by different methods and suspended in gelatin films or D2O solutions. The PL dynamics of SWNTs depends on the local environment surrounding the SWNTs rather than the synthesis methods. The very weak temperature dependence of PL and the environment-dependent PL reveal that the PL relaxation process is dominated by the interplay between free excitons and weakly localized excitons

Elevation of Pancreatic Enzymes in Gallbladder Bile Associated with Heterotopic Pancreas. A Case Report and Review of the Literature

Context This is the first report associating heterotopic pancreas in the gallbladder and elevated pancreatic enzymes in bile. Case report A 60-year-old woman underwent abdominal ultrasonography at a medical check-up, revealing a nodular protrusion at the neck of the gallbladder. It seemed likely to be a lymph node, but we could not exclude the possibility of gallbladder cancer. In order to make a correct diagnosis, laparoscopic cholecystectomy was successfully performed. Pathological examination revealed heterotopic pancreatic tissue in the gallbladder wall. In addition, we detected elevated levels of amylase and lipase in gallbladder bile. Conclusions Preoperative diagnosis of heterotopic pancreas in the gallbladder is difficult. However, an increase of pancreatic enzymes in gallbladder bile may potentially play an important role in the occurrence of acalculous cholecystitis and biliary cancer. We need more accumulation of cases to know the true significance of this anomaly