This is a past event.

Please join physics graduate student, Nayana Suresh Palaparambil for her presentation on Thursday, February 26 at 4 PM - Fisher Hall 139.

Nayana Suresh Palaparambil (Advisor: Ravi Pandey)

THEORETICAL STUDY OF LANTHANIDE-BENZENE COMPLEXES

Lanthanide elements (Ln = La–Lu) have attracted significant interest for their notable optical properties, while two-dimensional materials hold strong potential for nextgeneration devices due to their unique physical and chemical properties. Graphene is considered a suitable substrate for lanthanide-based complexes due to its high carrier mobility and favorable electronic properties. As a prototype for understanding these interactions, lanthanide–benzene (Ln–(Bz)) complexes were studied using density functional theory. We find that half of the complexes stabilize in lower-symmetry structures due to pseudo Jahn–Teller distortions, whereas metastable states are observed in Ho-(Bz), Er–(Bz), Tm–(Bz), and Yb-(Bz) complexes. Bonding analysis indicates significant
metal–ligand interactions, and natural population analysis suggests a dominant 6s → 5d electron transition that stabilizes these complexes. Spin multiplicity results show spin enhancement for La–(Bz), across the Pr–(Bz) to Tb–(Bz) series, and from Ho–(Bz) to Tm– (Bz) complexes, with spin quenching observed for Dy–(Bz). Optical absorption results indicate strong overlap between the diffuse lanthanide (5d) and the benzene (π) orbitals, resulting in large oscillator strengths and enhanced absorption intensity. Nonlinear optical properties show distinct trends in static linear polarizability (α₀), first hyperpolarizability (β₀), and second hyperpolarizability (γ₀) across the lanthanide series. Our results are expected to establish a framework for the use of lanthanide–graphene hybrids in advanced photonic technologies, such as optical limiters.