  We explored simultaneous observations of chromospheric evaporation and
condensation during the impulsive phase of a C6.7 flare on 9 May 2019. The
solar flare was simultaneously observed by multiple instruments, i.e., the New
Vacuum Solar Telescope (NVST), the Interface Region Imaging Spectrograph, the
Atmospheric Imaging Assembly (AIA), the Fermi, the Mingantu Spectral
Radioheliograph, and the Nobeyama Radio Polarimeters. Using the single Gaussian
fitting and the moment analysis technique, redshifted velocities at slow speeds
of 15-19 km/s are found in the cool lines of C II and Si IV at one flare
footpoint location. Red shifts are also seen in the H-alpha line-of-sight (LOS)
velocity image measured by the NVST at double footpoints. Those red shifts with
slow speeds can be regarded as the low-velocity downflows driven by the
chromospheric condensation. Meanwhile, the converging motions from double
footpoints to the loop top are found in the high-temperature EUV images, such
as AIA 131 A, 94 A, and 335 A. Their apparent speeds are estimated to be
roughly 126-210 km/s, which could be regarded as the high-velocity upflows
caused by the chromospheric evaporation. The nonthermal energy flux is
estimated to be about 5.7x10^10 erg/s/cm^2. The characteristic timescale is
roughly equal to 1 minute. All these observational results suggest an explosive
chromospheric evaporation during the flare impulsive phase. While a
HXR/microwave pulse and a type III radio burst are found simultaneously,
indicating that the explosive chromospheric evaporation is driven by the
nonthermal electron.
