Spectroscopy of C60+ and C120+ in the mid-infrared.

Infrared spectra of C60+ and C120+, obtained via helium messenger spectroscopy, are reported. For C60+, new absorption features have been found just above the discrete vibrational spectrum of the ion. The absorption profile, which is broad and contains little structure, is assigned to one or more electronic absorption transitions and is in good agreement with predictions from time-dependent density functional theory. It seems likely that the transitions observed correspond to excitation from the 2A1u electronic ground state to one or both of the low-lying 2E1u and 2E2u electronic states previously identified as dark states of C60+. These states presumably become optically bright through vibronic coupling and specifically the Jahn-Teller effect. In the case of C120+, the simplest positively charged oligomer of C60, we present the first vibrational spectrum of this ion. Through a comparison with theory, vibrational features are best explained by a peanut-shaped structure for C120+, maintained by covalent bonding between the two C60 units. We have also discovered electronic transitions for C120+, which, similar to C60+, lie just above the vibrational spectrum.

Electronic spectroscopy of cationic adamantane clusters and dehydrogenated adamantane in helium droplets.

We report the first helium-tagged electronic spectra of cationic adamantane clusters, along with its singly, doubly, and triply dehydrogenated analogues embedded in helium droplets. Absorption spectra were measured by recording the evaporation of helium atoms as a function of laser wavelength in the range of 300-2150 nm. Experimental spectra are coupled with simulated spectra obtained from quantum chemical calculations. The spectrum of cationic adamantane agrees with the electronic photodissociation spectrum measured previously, with an additional low-energy absorption at around 1000 nm. The spectra of the dehydrogenated molecules present broad absorptions exclusively in the high-energy region (300-600 nm). For the higher order adamantane dimer and trimer ions, strong absorptions are observed in the low-energy region (900-2150 nm), rationalised by transitions delocalised over two adamantane units.

Solvation of Large Polycyclic Aromatic Hydrocarbons in Helium: Cationic and Anionic Hexabenzocoronene.

The adsorption of helium on charged hexabenzocoronene (Hbc, C42H18), a planar polycyclic aromatic hydrocarbon (PAH) molecule of D6h symmetry, was investigated by a combination of high-resolution mass spectrometry and classical and quantum computational methods. The ion abundance of HenHbc+ complexes versus size n features prominent local anomalies at n = 14, 38, 68, 82, and a weak one at 26, indicating that for these "magic" sizes, the helium evaporation energies are relatively large. Surprisingly, the mass spectra of anionic HenHbc- complexes feature a different set of anomalies, namely at n = 14, 26, 60, and 62, suggesting that the preferred arrangement of the adsorbate atoms depends on the charge of the substrate. The results of our quantum calculations show that the adsorbate layer grows by successive filling of concentric rings that surround the central benzene ring, which is occupied by one helium atom each on either side of the substrate. The helium atoms are fairly localized in filled rings and they approximately preserve the D6h symmetry of the substrate, but helium atoms in partially filled rings are rather delocalized. The first three rings contain six atoms each; they account for magic numbers at n = 14, 26, and 38. The size of the first ring shrinks as atoms are filled into the second ring, and the position of atoms in the second ring changes from hollow sites to bridge sites as atoms are filled into the third ring. Beyond n = 38, however, the arrangement of helium atoms in the first three rings remains essentially frozen. Presumably, another ring is filled at n = 68 for cations and n = 62 for anions. The calculated structures and energies do not account for the difference between charge states, although they agree with the measurements for the cations and show that the first solvation shell of Hbc± is complete at n = 68. Beyond that size, the adsorbate layer becomes three-dimensional, and the circular arrangement of helium changes to hexagonal.

Increased in-hospital mortality following severe head injury in young children: results from a nationwide trauma registry.

BACKGROUND: In the current literature, the outcome of paediatric brain injury is controversially discussed. According to the majority of the studies, there seems to be a decreased mortality but worse recovery in paediatric, traumatic brain injury in comparison with adults. However, there is a lack of information concerning the differences in various stages of development in patients younger than 18 years. The aim of our study was to verify the in-hospital outcome of different paediatric age groups in comparison to adults with respect to the treatment strategy. METHODS: We performed a retrospective analysis of the TraumaRegister DGU(®) from 2002 to 2012. Inclusion criteria were an Abbreviated Injury Scale (AIS) head ≥3 points and an AIS ≤2 points of the remaining body regions. The collective was divided into different subgroups according to age (1-3, 4-6, 7-10, 11-14, 15-17) and an adult control group aged between 18 and 55 years. We descriptively analysed the endpoint rate of sepsis, multiple organ failure, and mortality. Additionally, the Glasgow Outcome Scale (GOS) at discharge was observed. RESULTS: Overall, 1110 children and 6491 adult control patients were included. Comparing the rate of intubation on-scene, the rate of cranial CT scans, the rate of craniotomies, and the rate and length of intensive care treatment, we could only identify minor differences between the age groups. The treatment after discharge from hospital was markedly different due to a very low rate of in-patient rehabilitation treatment in children. On one hand, the rate of systemic complications, such as sepsis and multiple organ failure increased with increasing age. On the other hand, we found a significantly increased mortality in children younger than 7 years after very (AIS head = 5) severe brain injury. The in-hospital functional outcome in survivors, according to the GOS, was beneficial for younger children in comparison to adolescents and adults. CONCLUSIONS: We were unable to identify marked age-related differences in the therapeutic approach. Nevertheless, we were able to demonstrate marked differences of outcome. Children younger than 7 years significantly die more often due to direct impact of severe trauma. But if they survive, they seem to develop less systemic complications and profit from a better functional outcome.