Most theories of emotion, including Sartre's, are based on the idea that everything we need to know about emotion can be learned by studying the adult. Given that we can see in the face of the infant all the facial expressions that we will later associate with emotion in the adult, and given also that we are hard pressed to explain how the infant can make the kind of cognitive appraisals you require for adult emotion, how do you explain the phenomenology of infantile affect display? Furthermore, how do you explain the effect on emotion display and experience of such substances as booze, caffeine, reserpine, Prozac, cocaine, amphetamines, and Lithium?
As for Tomkins, he was born Silvan Samuel (or Solomon) Tomkins in 1911, worked at a number of universities in his career, published a great many books on his theory of emotion (called affect theory), and died at 80 in 1991. Should you want to learn more than we can communicate in the brief space of this WebSite, you might read the first section of my 1992 book "Shame and Pride" published by W.W. Norton. I suspect you'd find it interesting and would react to it in ways the rest of us might find interesting as well.