1：Experimental Design and Method Selection:

Two-photon photoassociation spectroscopy was used to probe the least-bound state of the ground molecular potential of 86Sr2. The experiment involved coupling colliding atoms to the least-bound state using two laser fields near resonance with an intermediate state bound in the 0u potential corresponding to the 1S0 + 3P1 asymptote.

2：The experiment involved coupling colliding atoms to the least-bound state using two laser fields near resonance with an intermediate state bound in the 0u potential corresponding to the 1S0 + 3P1 asymptote. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: Ultracold 86Sr atoms in a single-beam optical dipole trap were used. The sample temperature was set between 30 and 1000 nK, with typical atom numbers of several hundred thousand and peak densities up to 2×1012 cm?

3：List of Experimental Equipment and Materials:

A 1064-nm laser for the optical dipole trap, frequency-stabilized master laser for photoassociation beams, acousto-optic modulator for generating PA beams, and time-of-flight absorption imaging for measurement.

4：Experimental Procedures and Operational Workflow:

After atoms equilibrated in the optical dipole trap, PA lasers were applied. The PA spectrum was obtained by varying one laser frequency while holding the other fixed, leading to atom loss from the trap which was measured after an exposure time.

5：Data Analysis Methods:

The evolution of atom number with time was modeled to extract the molecular binding energy, considering collisional frequency shifts and ac Stark shifts.