  Measuring transient optical field is pivotal not only for understanding
ultrafast phenomena but also for quantitative detection of various molecular
species in a sample. In this work, we demonstrate near-petahertz electric field
detection of a few femtosecond pulses with 2oo attosecond temporal resolution,
10$^8$ detection dynamic range in electric field and sub-femtojoule detection
sensitivity, exceeding those reported by the current methods. By field-resolved
detection of the impulsively excited molecules in the liquid phase, termed
'femtosecond fieldoscopy', we demonstrate temporal isolation of the response of
the target molecules from those of the environment and the excitation pulse. In
a proof-of-concept analysis of aqueous and liquid samples, we demonstrate
field-sensitive detection of combination bands of 4.13 {\mu}mol ethanol for the
first time. This method expands the scope of aqueous sample analysis to higher
detection sensitivity and dynamic range, while the simultaneous direct
measurements of phase and intensity information pave the path towards
high-resolution biological spectro-microscopy
