• To study one-photon forbidden transitions to hitherto ( or previously ) inaccessible electronically excited molecular states, ...
• The sources discussed previously ( or before ) ...
• To study one-photon forbidden transitions to hitherto ( or previously ) inaccessible electronically excited molecular states, ...
• The sources discussed previously ( or before ) ...
Циммерман М., Веденеева К.. Русско-Английский научно-технический словарь переводчика. Russian-English scientific dictionary for translators. 2012