Questionnaire that measures participants emotion at the time of completion of the questionnaire Could anyone help with finding a questionnaire that measures participants emotion at the time of completion of the questionnaire about the effect on memory recall in eyewitness testimony?
Your question is very specific in that it pertains to memory recall in eyewitness testimony. But presumably the context is not the main point. The main point is that you want to get a measures of state emotion.

The most common measure that I'm familiar with is the PANAS (Watson, Clark, Tellegen, 1988). It asks about the frequency of experiencing a set of common positive and negative emotions. It yields overall scores positive affect and negative affect. It can be asked with different time-frame instructions (e.g., last hour, today, last week, etc.). Choose the time frame that most aligns with your construct of interest.

See also

https://en.wikipedia.org/wiki/Affect_measures

Watson, D.; Clark, L. A.; Tellegen, A. (1988). "Development and Validation of Brief Measures of Positive and Negative Affect: The PANAS Scales". Journal of Personality and Social Psychology. 54 (6): 1063–1070. doi:10.1037/0022-3514.54.6.1063.