  This study explores the Doppler shift at different wavelengths in the
Interface Region Imaging Spectrograph (IRIS) solar spectrum and implements a
comprehensive consideration of Doppler velocity oscillations in the IRIS
channels. This comprehensive consideration reveals a propagating periodic
perturbation in a large number of chromosphere and transition region (TR)
bright points (BPs). To our knowledge, this is the first investigation of the
longitudinal oscillations with damping in BPs using comprehensive consideration
of the Doppler velocity at various wavelengths. The phenomena of attenuation in
the red and blue Doppler shifts of the solar wavelength range were seen several
times during the experiments. We utilized deep learning techniques to examine
the statistical properties of damping in network and internetwork BPs, as well
as active, quiet areas, and coronal hole areas. Our results revealed varying
damping rates across different regions, with 80 percent of network BPs
exhibiting damping in quiet areas and 72 in coronal hole areas. In active
areas, the figure approached 33. For internetwork BPs, the values were 65, 54,
and 63 percent for quiet areas, coronal hole areas, and active regions,
respectively. The damping rate in active regions is twice as high at
Internetwork's BPs. The damping components in this study were computed, and the
findings show that the damping at all points is underdamped. The observed
damping process suggests the propagation and leaking of energetic waves out of
TR bright points, potentially contributing to the energy transport from the
bright magnetic footpoints to the upper chromosphere, transition region, and
corona.
