Sökning: "vibrational spectroscopy"

Visar resultat 36 - 40 av 170 avhandlingar innehållade orden vibrational spectroscopy.

1. 36. Synchrotron radiation induced fluorescence spectroscopy of gas phase molecules

   Författare :Jesús Álvarez Ruiz; Elisabeth Rachlew; J. E. Rubensson; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; molecular spectroscopy; photon induced fluorescence; synchrotron radiation; superexcited states; Fysik; Physics; Fysik;

   Sammanfattning : A new experimental set-up for gas phase fluorescence studies using synchrotron radiation has been designed and constructed to perform simultaneously total and dispersed fluorescence measurements. Neutral photodissociation of CO has been investigated after excitation with 19-26 eV photons. LÄS MER

3. 37. Dynamic local structural symmetries and luminescence properties of the yellow emitting phosphor Ce3+-doped Y3Al5O12

   Författare :Yuan-Chih Lin; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; free electron laser; neutron scattering; vibrational spectroscopy; phosphor; light emitting diode; luminescence; thermal quenching; garnet;

   Sammanfattning : This thesis centers on investigations of the local structure and vibrational properties of the oxide garnet Y3Al5O12 (YAG), which when substituted with a few percent of the activator ion Ce3+ to replace Y3+ (Y3−xCexAl5O12, YAG:Ce3+) is one of the most important phosphors for solid state lighting. The study builds on a comprehensive analysis of the nature of the phonons and localized vibrational modes in YAG:Ce3+ and how these depend on the Ce3+ concentration and temperature and how they affect key optical properties, such as the intensity and frequency of the emitted light. LÄS MER

4. 38. Upconversion Detection for Improved Nonlinear Mid-infrared Spectroscopy in Flames

   Författare :Rasmus Lyngbye Pedersen; Förbränningsfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; infrared; upconversion; degenerate four wave mixing; hydrogen cyanide; polarisation spectroscopy;

   Sammanfattning : This thesis deals with the addition of upconversion detection to non-linear mid-infrared laser spectroscopy techniques. The techniques investigated here are degenerate four wave mixing (DFWM) and infrared polarization spectroscopy (IRPS). LÄS MER

5. 39. Structure, interactions and functionality in novel electrolyte materials for fuel cell applications

   Författare :Anna Martinelli; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; proton conductivity; ionic liquids; Polymer electrolyte membrane PEM ; fuel cell; vibrational spectroscopy;

   Sammanfattning : It is today well known that fossil fuels will sooner or later be depleted, and the need to find alternative energy sources is now accepted. Among the diverse technologies developed to produce energy, considerable interest is currently directed to the hydrogen fuel cell, a device that converts chemical into electrical energy, is versatile and has a low environmental impact. LÄS MER

7. 40. Spontaneous and stimulated X-ray Raman scattering

   Författare :Yu-Ping Sun; Faris Gel'mukhanov; Vincenzo Carravetta; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; resonant X-ray scattering; resonant Auger scattering; rotational Doppler broadening; XFEL pulse; Atomic and molecular physics; Atom- och molekylfysik; Spectroscopy; Spektroskopi;

   Sammanfattning : The present thesis is devoted to theoretical studies of resonant X-ray scattering and propagation of strong X-ray pulses. In the first part of the thesis the nuclear dynamics of different molecules is studied using resonant X-ray Raman and resonant Auger scattering techniques. LÄS MER