In this work, more than 130 line peaks in electron spin resonance (ESR)
spectra have been discovered of the laser material MgF2 crystal in
room-temperature experiments. A sample is cut from the shoulder part of the
MgF2 crystal and another is from the MgF2:Co crystal. The
samples were not treated by any irradiation. The same
anisotropic ESR spectra of the two samples indicate that the dopant
Co2+ introduces
defects which induce the same multinuclear free radicals as in dislocations in
the sample of MgF2. These paramagnetic solid multinuclear free radicals
show good stability and their ESR spectra are found to be anisotropic. ESR
signals are derived from three different types of multinuclear free radicals
from a tentative simulation analysis.
When the direction of the applied magnetic field is along the [100] or [010]
orientation of the crystal, the magnetic field at which the ESR signals are
detected ranges from 0.2294T to 0.4654T and the width of this range is 0.2362T
(corresponding to an energy band of 0.233eV); the most narrow peak in
the ESR
spectra has a width ΔH about 1.28×10−3T. This
width ΔH, equivalent to the energy difference of two neighbouring
levels, is very small, only 1.85×10−7eV (or 1.46×10−3cm−1).
This fact indicates that the ground state is highly degenerate and
splits
into nearly quasi-continuous energy levels like an energy band in an applied
magnetic field. It may be served as a new starting point of solid laser
exciter frequency modulation.