Detaching ultrathin Bi films from the mica substrate will be difficult. You can try heating it. Due to any thermal mismatch if the film detaches your are lucky.

Alternately,

I would suggest your user to grow the same Bi metal film on a NaCl substrate. You can then carefully dip one end of the substrate into distilled water, the film would then detach and begin to float, the whole film may break up also into small areas.

Don't disturb the water surface. Very Gently dip your your Cu grid underneath the floating Bi film, and pick it up. You may have to try a couple of times to be successful.

Dear Sheri Singerling

I have put together some thoughts here for you. I have provided some videos for explanation which might be useful.

Detaching a thin film from a substrate and attaching it to a Cu mesh grid for TEM analysis can be challenging, but there are several techniques you can try. Mechanical exfoliation, wet transfer, chemical etching, and laser lift-off are all viable options that can be optimized for your specific sample.

Let me explain these methods one by one:

Mechanical exfoliation: This method involves using adhesive tape to peel off the thin film from the mica substrate. You can place the tape on the sample and gently peel it off, and the thin film should come off with the tape. The thin film can then be transferred to a Cu mesh grid by gently pressing it onto the grid with a tweezer or a soft brush. This method may not work well if the adhesion between the thin film and the substrate is too strong. This youtube video explains Exfoliating 2D materials using a scotch tape! - YouTube

Wet transfer: This method involves immersing the sample in a liquid that can weaken the adhesion between the thin film and the substrate. One such liquid is distilled water, which can be used to float the thin film off the mica substrate. You can place the sample face down on the surface of the water and wait for the thin film to detach from the substrate. The thin film can then be transferred to a Cu mesh grid by placing the grid on top of the floating film and gently lifting it off the water surface. Another option is to use a surfactant or a detergent to weaken the adhesion between the thin film and the substrate. This method may require some optimization of the surfactant or detergent concentration and exposure time. This youtube video explains HGW Wet Transfers Step by Step Manual - YouTube

Chemical etching: This method involves using a chemical that can selectively etch away the substrate while leaving the thin film intact. One such chemical for mica is hydrofluoric acid (HF), which can dissolve the mica substrate. You can immerse the sample in a dilute solution of HF and wait for the substrate to dissolve, leaving the thin film floating in the solution. The thin film can then be transferred to a Cu mesh grid using a similar procedure as the wet transfer method. This method requires careful handling of the HF solution, which can be hazardous. Youtube video Chemical Etching: A Tour Through The Process (3D Animation) - YouTube

Laser lift-off: This method involves using a pulsed laser to selectively ablate the interface between the thin film and the substrate, allowing the thin film to be lifted off the substrate. This method requires specialized equipment, and the laser parameters need to be optimized for the specific sample.

The literature reference sounds like it's supposed to float off the mica? Score the edges, gently immerse at a 45 degree angle? This works with carbon films.