NFAP writing experiments. Tested the validity of Au substrates. Checked inks (MHA in acetonitrile; MHA in the mixture of acetonitrile and water). [1400:0000]

• Exp 1: Old commercial tip coated by immersing into a solution of MHA in acetonitrile (high concentration). Relative humidity ~17% without regulation). Writing was done, but topography also showed some relief where LFM image exists. Thought that molecules are stacked. Decided to try solution in CH3CN + H2O.
• Exp 2: New commercial tip coated by immersing into a solution of MHA in CH3CN + H2O. Tried under relative humidity of ~17%, 50~60% (regulated). Didn't work.
• Exp 3: Immersed the tip used in Exp 2 into the solution in Exp 1. Didn't work under any relative humidity (~17%, 50~60%). PSD signal started floating unstably with no reason before engagement.