A spectroscopic survey for lambda Bootis stars II. The observational data

lambda Bootis stars comprise only a small number of all A-type stars and ar e characterized as nonmagnetic, Population I, late B to early F-type dwarfs which show significant underabundances of metals whereas the light element s (C, N, O and S) are almost normal abundant compared to the Sun. In the se cond paper on a spectroscopic survey for lambda Bootis stars, we present th e spectral classifications of all program stars observed. These stars were selected on the basis of their Stromgren uvby beta colors as lambda Bootis candidates. In total, 708 objects in six open clusters, the Orion OB1 assoc iation and the Galactic field were classified. In addition, 9 serendipity n on-candidates in the vicinity of our program stars as well as 15 Guide Star Catalogue stars were observed resulting in a total of 732 classified stars . The 15 objects from the Guide Star Catalogue are part of a program for th e classification of apparent variable stars from the Fine Guidance Sensors of the Hubble Space Telescope. A grid of 105 MK standard as well as "pathol ogical" stars guarantees a precise classification. A comparison of our spec tral classification with the extensive work of Abt & Morrell (1995) shows n o significant differences. The derived types are 0.23 +/-0.09 (rms error pe r measurement) subclasses later and 0.30 +/-0.08 luminosity classes more lu minous than those of Abt & Morrell (1995) based on a sample of 160 objects in common. The estimated errors of the means are +/-0.1 subclasses. The cha racteristics of our sample are discussed in respect to the distribution on the sky, apparent visual magnitudes and Stromgren uvby beta colors.