Multiple experimental studies utilizing techniques such as X-ray diffraction, spectroscopy, and microscopy provide clear evidence supporting the existence and characterization of zwitterions.
The claim asserts that there is experimental evidence supporting the existence of zwitterions. Papers [3], [7], and [11] all explicitly provide experimental characterization (such as XRD, vibrational spectroscopy, and STM) of zwitterionic compounds. There are no papers refuting the claim, making the balance strongly supported.