A mechanism of light emission from a single bubble sonoluminescence (SBSL)
was formulated by assuming that the source for the light emission is bremss
trahlung in partially ionized gases. This emission mechanism turns out to b
e same as the black body radiation with finite absorption, which confirms t
hat the principal mechanism of SBSL is bremsstrahlung with slight black bod
y emission nature. Also the spectrum was measured and the observed results
were compared with the calculated ones. Calculated and experimental results
yield common spectral behavior in the visible region: the spectral radianc
e shows pou er-law dependence on wavelength with an exponent of -2.5. The S
BSL spectrum which is characterized by the continuous one with no major pea
ks has been confirmed experimentally. The bubble dynamics model proposed al
so takes account the afterpulse characteristics of SBSL.