where ε0 is the permittivity of vacuum, k is the spring constant of the cantilever, rtip is the tip radius, and RJ is the resistance responsible for Joule heat. The value of RJ can be evaluated from the proportional coefficient in the relationship between DJ and ∆fele. In this study, we evaluate the surface resistance of a gold (Au) film on mica in an ultrahigh vacuum (UHV) with a tungsten (W) tip sharpened by high-temperature flame-etching; rtip was estimated by field electron emission in the UHV. The W tip is on a quartz-tuning-based retuned force sensor with a high Q. We will discuss the validity of the equation. 68Charge separation at interfaces plays a crucial role in various devices. In the case of nanoparticle or thin organic molecular layer interfaces, it is essential to consider the overall system charge involved in charge separation and recombination, which differs from bulk materials due to the limited number and mobility of carriers. Our goal is to observe charge transfer dynamics and discuss the energy level alignment at interfaces composed of a small number of molecules. In this study, we fabricated a monolayer of the conducting polymer Poly(9,9-dioctylfluorenyl-alt-bithiophene) (F8T2) on a TiO2 substrate, focusing on an interface with a minimal number of molecules. We investigated the photoexcited charge separation dynamics at the interface using Kelvin Probe Force Microscopy (KPFM) and Electrostatic Force Microscopy (EFM). EFM measurements at various applied DC voltages demonstrated a voltage-dependent optical response in the time evolution of charge separation. We analyzed the time evolution of charge separation using a model based on the energy alignment of the interface, taking into account the limited number of molecules involved in the charge separation reaction. The conservative and non-conservative forces between a tip and a sample can be simultaneously estimated by frequency modulation atomic force microscopy (FM-AFM). The conservative forces are derived from the resonance frequency shift (∆f) of an oscillating AFM cantilever; f is the cantilever’s resonance frequency. The non-conservative forces are detected as the dissipation energy (D), derived from the change in the amplitude of the excitation signal to maintain a constant amplitude (A) of the cantilever oscillation. Previously, we reported that the dissipation energy (DJ) due to Joule heat was proportional to ∆fele due to the long-range electrostatic force under a bias voltage (V) between the tip and sample, as the following equation, notably excluding V and Poster Award NomineeP3-11EFM, KPFM Measurement of Photo-induced Charge Separation on F8T2 Monolayer/ TiO2 Interface Tomoki Misaka1, Naoki Hara2, Hiroshi Ohoyama1, Shusaku Nagano2, and Takuya Matsumoto1 1 Department of Chemistry Graduate school of Science, Osaka University2 Department of Chemistry, College of Science, Rikkyo UniversityP3-12Surface Resistivity Measurements Using Frequency Modulation Atomic Force Microscopy in Ultrahigh Vacuum Naoki Shima1, Takahiro Kato1, Masahiko Tomitori2, and Toyoko Arai1 1 Kanazawa University,2 Japan Advanced Institute of Science and Technology the tip-sample separation: [1] 𝐷𝐷𝐷𝐷𝐽𝐽𝐽𝐽=−16𝜋𝜋𝜋𝜋3𝜀𝜀𝜀𝜀0𝑘𝑘𝑘𝑘𝐴𝐴𝐴𝐴2𝑟𝑟𝑟𝑟tip×𝑅𝑅𝑅𝑅J×∆𝑓𝑓𝑓𝑓ele[1] T. Arai, D. Kura, R. Inamura & M. Tomitori, Jpn. J. Appl. Phys., 57, 08NB04 (2018).
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