Abstract: An MT-TOFMS which is one mode of the present invention includes: a linear ion trap (2) configured to temporarily hold ions to be analyzed, and to eject the ions through an ion ejection opening (211) having a shape elongated in one direction; a loop flight section (3) configured to form a loop path (P) capable of making ions repeatedly fly; and a slit part (5) located on an ion path in which the ions ejected from the linear ion trap (2) travel until the ions are introduced into the loop path, the slit part configured to block a portion of the ions in a longitudinal direction of the ion ejection opening (211).

Abstract: A thermosensitive recording sheet having a coated film containing a color-forming lactone compound, an acidic substance and a sensitizer. The sensitizer is at least one aliphatic carboxylic acid ester represented by the formula ##STR1## wherein R.sup.1 and R.sup.2 are identical or different and each represents an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, an aryl group, a group of the formula --C.sub.n H.sub.2n --Ar in which n is an integer of 1 to 8 and Ar is an aryl group, or a group of the formula --C.sub.n H.sub.2n --CO--Ar in which n and Ar are as defined; R.sup.3 represents a group of the formula --C.sub.n H.sub.2n --in which n is as defined; R.sup.4 and R.sup.5 are identical or different and each represents an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, a group of the formula --C.sub.n H.sub.2n --Ar in which n and Ar are as defined, or a group of the formula --C.sub.n H.sub.2n --CO--Ar in which n and Ar are as defined; and R.sup.