travel time, \(t_{\text{tv}}\)

in flame emission and absorption spectrometry
https://doi.org/10.1351/goldbook.T06493
The time needed for the component to be carried from the burner tip to the observation space (in \(\mathrm{s}\)). Travel time depends on the observation height and the flame rise velocity.
Source:
PAC, 1986, 58, 1737. (Quantities and units in clinical chemistry: Nebulizer and flame properties in flame emission and absorption spectrometry (Recommendations 1986)) on page 1742 [Terms] [Paper]