20 research outputs found
Investigation of neural network architectures for stepwise classification of multi-attribute LIBS spectra under martian conditions
Neural Networks for Stepwise Classification of LIBS Spectra under Simulated Martian Conditions
Investigating neural network architectures for stepwise classification of multi-attribute LIBS spectra under Martian conditions
Time-Dependent Friction Effects on Vibrational Infrared Frequencies and Line Shapes of Liquid Water
From ab initio simulations of liquid water, the time-dependent friction functions and time-averaged nonlinear effective bond potentials for the OH stretch and HOH bend vibrations are extracted. The obtained friction exhibits not only adiabatic contributions at and below the vibrational time scales but also much slower nonadiabatic contributions, reflecting homogeneous and inhomogeneous line broadening mechanisms, respectively. Intermolecular interactions in liquid water soften both stretch and bend potentials compared to the gas phase, which by itself would lead to a red-shift of the corresponding vibrational bands. In contrast, nonadiabatic friction contributions cause a spectral blue shift. For the stretch mode, the potential effect dominates, and thus, a significant red shift when going from gas to the liquid phase results. For the bend mode, potential and nonadiabatic friction effects are of comparable magnitude, so that a slight blue shift results, in agreement with well-known but puzzling experimental findings. The observed line broadening is shown to be roughly equally caused by adiabatic and nonadiabatic friction contributions for both the stretch and bend modes in liquid water. Thus, the quantitative analysis of the time-dependent friction that acts on vibrational modes in liquids advances the understanding of infrared vibrational frequencies and line shapes
Measurement of the mass difference m(D-s(+))-m(D+) at CDF II
We present a measurement of the mass difference m(D-s(+))-m(D+), where both the D-s(+) and D+ are reconstructed in the phipi(+) decay channel. This measurement uses 11.6 pb(-1) of data collected by CDF II using the new displaced-track trigger. The mass difference is found to be m(D-s(+))-m(D+)=99.41+/-0.38(stat)+/-0.21(syst) MeV/c(2)
Machine Learning for Planetary In-Situ Spectroscopic Data
Summary of planned activities of the newly founded DLR junior research group "Machine learning for planetary in-situ spectroscopic data
Investigation of Neural Network Architectures for Classification of Multi-Attribute LIBS Spectra Under Simulated Martian Atmospheric Conditions
We compare two neural network classification schemes for predicting two chemical compenents of self-prepared samples, measured with our dedicated LIBS setup
Time-dependent friction effects on vibrational infrared frequencies and line shapes of liquid water
From ab initio simulations of liquid water, the time-dependent friction functions and time-averaged
non-linear effective bond potentials for the OH stretch and HOH bend vibrations are extracted. The
obtained friction exhibits adiabatic contributions at and below the vibrational time scales, but also
much slower non-adiabatic contributions, reflecting homogeneous and inhomogeneous line broadening
mechanisms, respectively. Compared to the gas phase, hydration softens both stretch and bend
potentials, which by itself would lead to a red-shift of the corresponding vibrational bands. In
contrast, non-adiabatic friction contributions cause a spectral blue shift. For the stretch mode, the
potential effect dominates and thus a significant red shift when going from gas to the liquid phase
results. For the bend mode, potential and non-adiabatic friction effects are of comparable magnitude,
so that a slight blue shift results, in agreement with well-known but puzzling experimental findings.
The observed line broadening is shown to be roughly equally caused by adiabatic and non-adiabatic
friction contributions for both, the stretch and bend modes in liquid water. Thus, the understanding
of infrared vibrational frequencies and line shapes is considerably advanced by the quantitative
analysis of the time-dependent friction that acts on vibrational modes in liquid