A cryogen-free low temperature scanning probe microscope system for ångström-resolved spectroscopic imaging

We report the development of a cryogen-free, low-temperature optical-coupled scanning probe microscope (LT-OC-SPM) designed for high-resolution multimodal imaging and spectroscopy. To mitigate the mechanical vibrations from the cryocooler cold head, we implement a remote liquefaction scheme that effectively decouples the noise from the tunneling junction. The system achieves a stable base operation temperature below 3 K and a tunneling current noise level under 20 fA/Hz 1/2 , comparable to the performance of the conventional SPM systems employing bath cryostats. Moreover, our system features a customized rigid scanner integrated with in-vacuo piezo-driven high-numerical aperture lenses, facilitating simultaneous topographic and spectroscopic measurements. Multimodal characterization of silver phthalocyanine (AgPc) molecules on Ag(110) demonstrates ångström scale probing of intramolecular structure and localized vibrational modes, highlighting the versatility of our system in high-resolution surface characterization. Consequently, this remote liquefaction architecture provides a sustainable, high-performance cryogen-free platform for ångström-resolved spectroscopic imaging, establishing a robust foundation for future multifunctional near-field optical spectroscopy.