Preferred Label : magic angle;
IUPAC acronym : NMR;
IUPAC definition : Upon excitation of an 'isotropic' sample (assuming an ultra short excitation pulse)
the relationship between the fluorescence intensity detected at a time t and through
a polarization analyser oriented at an angle β with respect to the electric polarization
of the exciting beam is given by \[I(t,\beta ) \propto N(t)\left [ 1 (3\, {cos}
{2}\, \beta - 1)R(t) \right ]\] where R(t) is the degree of alignment of the emitting
transition dipole in the laboratory frame and N(t) is the excited-state population,
both at time t. For β 54.7 (the magic angle), the dipole-alignment contribution
vanishes and I(t,β 54.7 ) Nt.;
Scope note : the term magic angle is also used in nmr spectroscopy.; applies for steady-state measurements on fixed samples. in this case iß ?
n 1 3 ß
2 1 r with iß the intensity of the effect observed at an
analyser angle ß with respect to the electric polarization of the exciting beam,n
the excited-state population at steady-state equilibrium, and r the degree of alignment
of the transition (dipole) moment of the excited molecular entity.; this concept also applies for time-resolved absorption measurements in cases in which
photoselection occurs because the detected species do not freely rotate fast enough
to make the measurement isotropic within the time of the experiment.;
Origin ID : MT07419;
Automatic exact mappings (from CISMeF team)
- False automatic mappings
- See also
Upon excitation of an 'isotropic' sample (assuming an ultra short excitation pulse)
the relationship between the fluorescence intensity detected at a time t and through
a polarization analyser oriented at an angle β with respect to the electric polarization
of the exciting beam is given by \[I(t,\beta ) \propto N(t)\left [ 1 (3\, {cos}
{2}\, \beta - 1)R(t) \right ]\] where R(t) is the degree of alignment of the emitting
transition dipole in the laboratory frame and N(t) is the excited-state population,
both at time t. For β 54.7 (the magic angle), the dipole-alignment contribution
vanishes and I(t,β 54.7 ) Nt.
