4140
When the time scale for interconversion is long enough for isolation of individual rotamers ( usually arbitrarily defined as a half-life of interconversion of 1000 seconds or longer ) , the isomers are termed " atropisomers " ( " see : " atropisomerism ) .
 time: half-life
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 time: half-life