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MnII

Mn II denotes the singly ionized manganese ion, Mn+. In astronomical spectroscopy it is a prominent diagnostic species because its lines appear in a range of environments from stellar atmospheres to the interstellar medium and quasar absorption systems.

The ground-state configuration of Mn II is conventionally described as arising from a partially filled 3d shell,

Mn II forms in environments where the radiation field and temperature are sufficient to ionize neutral manganese

In practice, Mn II data—including precise wavelengths, energy levels, and oscillator strengths—are compiled in atomic databases

reflecting
a
complex
level
structure
with
many
low-lying
energy
levels.
This
leads
to
a
rich
spectrum
with
numerous
transitions
spanning
the
ultraviolet
and
visible
regions.
Among
the
strongest
features
are
ultraviolet
resonance
lines
and
several
multiplets
that
are
widely
used
to
determine
manganese
abundances
and
physical
conditions
in
astrophysical
sources.
to
Mn+.
This
includes
hot
stellar
atmospheres,
particularly
early-type
stars,
and
diffuse
gas
where
the
ionization
parameter
allows
Mn
II
to
be
relatively
abundant.
In
the
interstellar
and
circumstellar
media,
Mn
II
lines
are
valuable
tracers
of
chemical
enrichment
and
dust
depletion,
since
manganese
can
follow
different
depletion
patterns
compared
with
other
metals.
and
used
to
model
spectra.
These
lines
enable
measurements
of
manganese
abundances
in
stars
and
galaxies,
contributing
to
studies
of
stellar
nucleosynthesis,
galactic
chemical
evolution,
and
the
chemical
composition
of
the
early
universe.