The elegant Folger Shakespeare Library provided an intimate atmosphere Saturday evening for the persuasive young French duo of violinist Olivier Charlier and pianist Pascal Devoyon. In a program of violin sonatas ranging from Beethoven to Prokofiev, they executed the various musical demands with obvious confidence and e'lan and, consequently, more than lived up to the generous praises that have been bestowed upon them.

Charlier and Devoyon possess all the requisite virtuosic tools: flawless technique, suppleness of phrasing and poetic expressiveness. Each plays with a delicate, singing tone decidedly Gallic in temperament. As a team, they complement one another beautifully, with an extrasensory feel for give-and-take that belies their limited tenure as chamber music partners.

Beethoven's Violin Sonata No. 5 in F ("Spring"), with its sunny dialogue between instruments, Mozartean melodic flavor in the Adagio and subtle dynamic shadings throughout, presented a challenge they easily met. By contrast, the agitated and vigorous tonal clashings of Prokofiev's Sonata No. 2 dictated that each delve into his own bag of tricks, as Charlier's authoritative spiccato bowing confronted the turbulent sonic clusters entrusted to Devoyon.

They seemed, quite understandably, to be most attuned to the Sonata in A Major by Cesar Franck, who is regarded as the father of modern French chamber music. This piece requires a broad, logical concept of the work as a whole, so that the cyclical thematic fragments are not lost in the passionate outpourings that leap forth in the brooding minor melodic strands of the second movement. Charlier and Devoyon exhibited just such farsightedness, as even the reflective Recitative-Fantasia stood out, yet firmly within the sonata's design.