  Models of infrared spectra of Type Ia supernovae around maximum light are
presented. The underlying dynamic models are delayed detonation explosions in
Chandrasekhar mass carbon/oxygen white dwarfs. In combination with the
radiative transport codes employed here, these models provide plausible fits to
the optical spectra of "normal" Type Ia supernova. Two independent radiative
transport codes are used, one that assumes LTE and one that computes non-LTE
excitations and ionization. The models are compared with infrared data
available in the literature. The independent codes give a reasonable
representation of the data and provide physical explanations for their origin
independent of the detailed assumptions of the radiative transfer. The infrared
gives an especially powerful diagnostic of the dynamic model because with
strongly variable line blanketing opacity it probes different depths within the
exploded white dwarf at the same epoch. The velocity of the transition zone
between explosive oxygen and carbon burning can be directly determined. The
velocity at which the burning to nickel stops can also be probed. These
velocities are very sensitive to the explosion physics.
