ABSTRACT
Site-selective probing of iodine 4d orbitals at 13.1 nm was used to characterize the photolysis of CH2I2 and CH2BrI initiated at 202.5 nm. Time-dependent fragment ion momenta were recorded using Coulomb explosion imaging mass spectrometry and used to determine the structural dynamics of the dissociating molecules. Correlations between these fragment momenta, as well as the onset times of electron transfer reactions between them, indicate that each molecule can undergo neutral three-body photolysis. For CH2I2, the structural evolution of the neutral molecule was simultaneously characterized along the C-I and I-C-I coordinates, demonstrating the sensitivity of these measurements to nuclear motion along multiple degrees of freedom.
ABSTRACT
Polycyclic aromatic hydrocarbons (PAHs) play an important role in interstellar chemistry and are subject to high energy photons that can induce excitation, ionization, and fragmentation. Previous studies have demonstrated electronic relaxation of parent PAH monocations over 10-100 femtoseconds as a result of beyond-Born-Oppenheimer coupling between the electronic and nuclear dynamics. Here, we investigate three PAH molecules: fluorene, phenanthrene, and pyrene, using ultrafast XUV and IR laser pulses. Simultaneous measurements of the ion yields, ion momenta, and electron momenta as a function of laser pulse delay allow a detailed insight into the various molecular processes. We report relaxation times for the electronically excited PAH*, PAH+* and PAH2+* states, and show the time-dependent conversion between fragmentation pathways. Additionally, using recoil-frame covariance analysis between ion images, we demonstrate that the dissociation of the PAH2+ ions favors reaction pathways involving two-body breakup and/or loss of neutral fragments totaling an even number of carbon atoms.
ABSTRACT
OBJECTIVES: Advanced gallbladder carcinoma is associated with a dismal long term prognosis. The aim of the present study was to evaluate the effectiveness of radical surgery in advanced stages of gallbladder carcinoma. METHODS: The course of 66 patients operated for advanced gallbladder carcinoma was evaluated in a retrospective study; 14% of patients had stage II, 29% had stage III, and 57% had stage IV tumors. Twelve patients underwent cholecystectomy (CHE) and lymphadenectomy of the hepatoduodenal ligament (LA); 17 patients underwent cholecystectomy combined with segment IV/V liver resection (CHE+LR) and LA; and 10 patients underwent right extended hemihepatectomy (EHH). Complete tumor resection (R0) was achieved in six patients with CHE and LA, in 14 patients with CHE combined with segment IV/V LR and LA, and in all patients with right EHH. Resections with microscopic residual tumor (R1) were performed in nine patients. Mean follow-up was 15.4 months (range 3-90 months). RESULTS: The perioperative mortality rate was 1.5%, and the morbidity rate was 20%. In R0 resections, mean survival was 23.3, 25.0, and 26.3 months for the patients who underwent CHE and LA, CHE combined with segment IV/V LR and LA, and right EHH, respectively. After 24 months, 46.4% of the patients with R0 resection were still alive compared with none of the patients with residual tumor. In the patients with R0 resection, no difference in survival was detected when node-negative status (pN0) was compared with positive locoregional lymph nodes (pN1a), whereas the degree of dedifferentiation (G2/G3) influenced survival. CONCLUSIONS: If complete resection is achieved, radical surgical procedures, including segment IV/V liver resection and extended right hepatectomy, significantly improve survival rates with an acceptable morbidity and mortality rate.
