  The transverse momentum spectra of $\pi^{-}$, $\pi^{+}$, $K^{-}$, $K^{+}$,
$\bar{p}$, and $p$ produced in Au+Au collisions at center-of-mass energy
$\sqrt{s_{NN}}=7.7$, 11.5, 19.6, 27, 39, 62.4, 130, and $200$ GeV are analyzed
in the framework of a multisource thermal model. The experimental data measured
at midrapidity by the STAR Collaboration are fitted by the (two-component)
standard distribution. The effective temperature of emission source increases
obviously with the increase of the particle mass and the collision energy. At
different collision energies, the chemical potentials of up, down, and strange
quarks are obtained from the antiparticle to particle yield ratios in given
transverse momentum ranges available in experiments. With the increase of
logarithmic collision energy, the chemical potentials of light flavor quarks
decrease exponentially.
