  Kagome system usually attracts great interest in condensed matter physics due
to its unique structure hosting various exotic states such as superconductivity
(SC), charge density wave (CDW), and nontrivial topological states. Topological
semimetal RbTi3Bi5 consisting of the kagome layer of Ti shares a similar
crystal structure to topological correlated materials AV3Sb5 (A = K, Rb, Cs)
but with the absence of CDW and SC. Systematic de Haas-van Alphen (dHvA)
oscillation measurements are performed on the single crystals of RbTi3Bi5 to
pursue nontrivial topological physics and exotic states. Combining with
theoretical calculations, detailed Fermi surface topology and band structure
are investigated. A two-dimensional (2D) Fermi pocket \b{eta} is revealed with
a light-effective mass in consistent with the semimetal predictions. Landau Fan
of RbTi3Bi5 reveals a zero Berry phase for the \b{eta} oscillation in contrast
to that of CsTi3Bi5. These results suggest the kagome RbTi3Bi5 is a good
candidate to explore nontrivial topological exotic states and topological
correlated physics.
