Search results for "iTED"

Collision induced dissociation of stored gold cluster ions

1994

The stability of gold cluster ions Au + (2≦n≦23) has been investigated via collision induced dissociation in a Penning trap. Threshold energies and dissociation channels have been determined. The cluster stability exhibits a pronounced odd — even alternation: Clusters with an odd number of atoms,n, are more stable than the even-numbered ones. Enhanced stabilities are found for Au 3 + , Au 9 + , and Au 19 + in accordance with the Clemenger-Nilsson and the deformed jellium model of delocalized valence electrons. Excited odd cluster ions withn≦15 predominantly decay by evaporation of dimers; all others decay by monomer evaporation. From the dissociation channels estimates of the binding energi…

Fragmentation pattern of gold clusters collided with xenon atoms

1994

Abstract The dissociation channels of gold cluster ions Au n + (2 ≤ n ≤ 23) have been investigated via collision induced dissociation in a Penning trap. Excited odd cluster ions with n ≤ 15 decay by evaporation of dimers, all others decay by monomer evaporation. Information on the binding energies is deduced from these dissociation channels.

Photo fragmentation of metal clusters stored in a penning trap

1996

Photo fragmentation studies of stored mass selected metal cluster ions of a large size range are reported. The experimental method and the data evaluation are described in detail. Gold cluster ions were produced by laser vaporization and stored in a Penning trap. After size selection they were electronically excited by irradiation with a pulsed laser beam. Relaxation by evaporation of neutral atoms and dimers was observed as a function of photon energy. From these data upper and lower limits for dissociation energies are determined for Aun + (n=3 to 23).

A Stochastic Model for Population and Well-Being Dynamics

2014

This article presents a stochastic dynamic model to study the demographic evolution per sexes and the corresponding well-being of a general human population. The main model variables are population per sexes and well-being. The considered well-being variable is the Gender-Related Development Index (GDI), a United Nations index. The model's objectives are to improve future well-being and to reach a stable population in a country. The application case consists of adapting, validating, and using the model for Spain in the 2000–2006 period. Some instance strategies have been tested in different scenarios for the 2006–2015 period to meet these objectives by calculating the reliability of the res…

GFP-mut2 Proteins in Trehalose-Water Matrixes: Spatially Heterogeneous Protein-Water-Sugar Structures

2007

We report investigations on the properties of nanoenvironments around single-GFP-mut2 proteins in trehalose-water matrixes. Single-GFPmut2 molecules embedded in thin trehalose-water films were characterized in terms of their fluorescence brightness, bleaching dynamics, excited state lifetime, and fluorescence polarization. For each property, sets of approximately 100-150 single molecules have been investigated as a function of trehalose content and hydration. Three distinct and interconverting families of proteins have been found which differ widely in terms of bleaching dynamics, brightness, and fluorescence polarization, whose relative populations sizably depend on sample hydration. The r…

Quantifying Excess Deaths Related to Heatwaves under Climate Change Scenarios: A multicountry time series modelling study

2018

Background: Heatwaves are a critical public health problem. There will be an increase in the frequency and severity of heatwaves under changing climate. However, evidence about the impacts of climate change on heatwave-related mortality at a global scale is limited. Methods and findings: We collected historical daily time series of mean temperature and mortality for all causes or nonexternal causes, in periods ranging from January 1, 1984, to December 31, 2015, in 412 communities within 20 countries/regions. We estimated heatwave–mortality associations through a two-stage time series design. Current and future daily mean temperature series were projected under four scenarios of greenhouse g…

Laser synthesis of ultracold alkali metal dimers: optimization and control

2015

CERME7 Working group 17: From a study of teaching practices to issues in teacher education

2012

Around a quarter of WG17 papers focused on mathematical content knowledge needed for teaching (MCKT), trying to define it in relation to characteristics of the mathematical knowledge of other profe...

First-principles characterization of the singlet excited state manifold in DNA/RNA nucleobases

2020

An extensive theoretical characterization of the singlet excited state manifold of the five canonical DNA/RNA nucleobases (thymine, cytosine, uracil, adenine and guanine) in gas-phase is carried out with time-dependent density functional theory (TD-DFT) and restricted active space second-order perturbation theory (RASPT2) approaches. Both ground state and excited state absorptions are analyzed and compared between these different theoretical approaches, assessing the performance of the hybrid B3LYP and CAM-B3LYP (long-range corrected) functionals with respect to the RASPT2 reference. By comparing the TD-DFT estimates with our reference for high-lying excited states, we are able to narrow do…

Are the five natural DNA/RNA base monomers a good choice from natural selection?

2009

In order to prevent the damaging effects of sun radiation in the genetic material, its constituent chromophores, the five natural DNA/RNA nucleobases cytosine, thymine, uracil, adenine, and guanine, should be able to efficiently dissipate absorbed radiation, UV specifically, avoiding as much as possible photoreactions leading to lesions. It has been established experimentally and theoretically that efficient internal conversion channels, still open and relevant in the oligomer-stacked strands, exist in the monomers allowing an effective waste of the initial energy. Previous evidences cannot explain, however, why minor differences in the molecular structure modify drastically the photochemis…